feat: statcheck worker

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

Cargo.lock

@@ -1114,9 +1114,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.15.0"
+version = "0.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e087f84d4f86bf4b218b927129862374b72199ae7d8657835f1e89000eea4fb"
+checksum = "3a9bfc1af68b1726ea47d3d5109de126281def866b33970e10fbab11b5dafab3"
 
 [[package]]
 name = "heck"

ofborg/src/bin/mass-rebuilder.rs

@@ -2,8 +2,11 @@ use std::env;
 use std::error::Error;
 use std::path::Path;
 use std::process;
+use std::sync::RwLock;
 
 use async_std::task;
+use ofborg::config::VCSConfig;
+use ofborg::tasks::evaluate::SupportedVCS;
 use tracing::{error, info};
 
 use ofborg::checkout;
@@ -51,11 +54,16 @@ fn main() -> Result<(), Box<dyn Error>> {
         no_wait: false,
     })?;
 
+    let vcs_data = match cfg.vcs {
+        VCSConfig::GitHub => SupportedVCS::GitHub(RwLock::new(cfg.github_app_vendingmachine())),
+        VCSConfig::Gerrit => SupportedVCS::Gerrit,
+    };
+
     let handle = easylapin::WorkerChannel(chan).consume(
         tasks::evaluate::EvaluationWorker::new(
             cloner,
             &nix,
-            cfg.github_app_vendingmachine(),
+            vcs_data,
             cfg.acl(),
             cfg.runner.identity.clone(),
             events,

ofborg/src/bin/statcheck-worker.rs

@@ -0,0 +1,79 @@
+/// Statuses and checks worker
+/// - will keep a database of changes
+///     - their statuses
+///     - their checks
+/// - is VCS/CI agnostic
+use std::env;
+use std::error::Error;
+
+use async_std::task;
+use ofborg::config;
+use ofborg::easyamqp;
+use ofborg::easyamqp::ChannelExt;
+use ofborg::easyamqp::ConsumerExt;
+use ofborg::easylapin;
+use ofborg::tasks;
+use tracing::info;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    ofborg::setup_log();
+
+    let arg = env::args()
+        .nth(1)
+        .expect("usage: statcheck-worker <config>");
+    let cfg = config::load(arg.as_ref());
+
+    let conn = easylapin::from_config(&cfg.rabbitmq)?;
+    let mut chan = task::block_on(conn.create_channel())?;
+
+    // an RPC queue for verbs
+    let api_queue_name = "statcheck-api".to_owned();
+    // an event queue to be notified about statuses & checks changes.
+    let event_queue_name = "statcheck-events".to_owned();
+
+    chan.declare_exchange(easyamqp::ExchangeConfig {
+        exchange: api_queue_name.clone(),
+        exchange_type: easyamqp::ExchangeType::Topic,
+        passive: false,
+        durable: true,
+        auto_delete: false,
+        no_wait: false,
+        internal: false,
+    })?;
+
+    chan.declare_queue(easyamqp::QueueConfig {
+        queue: api_queue_name.clone(),
+        passive: false,
+        durable: true,
+        exclusive: false,
+        auto_delete: false,
+        no_wait: false,
+    })?;
+
+    chan.bind_queue(easyamqp::BindQueueConfig {
+        queue: api_queue_name.clone(),
+        exchange: api_queue_name.clone(),
+        routing_key: None,
+        no_wait: false,
+    })?;
+
+    let handle = easylapin::WorkerChannel(chan).consume(
+        tasks::statcheck_collector::StatusCheckCollector::new(cfg.statcheck.clone().db),
+        easyamqp::ConsumeConfig {
+            queue: api_queue_name.clone(),
+            consumer_tag: format!("{}-{}", cfg.whoami(), api_queue_name),
+            no_local: false,
+            no_ack: false,
+            no_wait: false,
+            exclusive: false,
+        },
+    )?;
+
+    info!("Waiting for API calls on {}", api_queue_name);
+    info!("Notifying of new changes on {}", event_queue_name);
+    task::block_on(handle);
+
+    drop(conn); // Close connection.
+    info!("Closed the session... EOF");
+    Ok(())
+}

ofborg/src/config.rs

@@ -12,6 +12,12 @@ use hubcaps::{Credentials, Github, InstallationTokenGenerator, JWTCredentials};
 use serde::de::{self, Deserialize, Deserializer};
 use tracing::{debug, error, info, warn};
 
+#[derive(Serialize, Deserialize, Debug)]
+pub enum VCSConfig {
+    GitHub,
+    Gerrit,
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Config {
     pub runner: RunnerConfig,
@@ -19,10 +25,16 @@ pub struct Config {
     pub checkout: CheckoutConfig,
     pub nix: NixConfig,
     pub rabbitmq: RabbitMqConfig,
-    pub github: Option<GithubConfig>,
-    pub github_app: Option<GithubAppConfig>,
+    pub vcs: VCSConfig,
     pub pastebin: PastebinConfig,
     pub log_storage: Option<LogStorage>,
+
+    // GitHub-specific configuration if vcs == GitHub.
+    pub github: Option<GithubConfig>,
+    pub github_app: Option<GithubAppConfig>,
+
+    // Gerrit-specific configuration if vcs == Gerrit.
+    pub gerrit: Option<GerritConfig>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -58,6 +70,21 @@ pub struct NixConfig {
     pub initial_heap_size: Option<String>,
 }
 
+const fn default_gerrit_ssh_port() -> u16 {
+    29418
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct GerritConfig {
+    // For HTTP API.
+    pub access_token_file: PathBuf,
+    // For event streaming.
+    pub ssh_private_key_file: PathBuf,
+    pub instance_uri: String,
+    #[serde(default = "default_gerrit_ssh_port")]
+    pub ssh_port: u16,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct GithubConfig {
     pub token_file: PathBuf,

ofborg/src/tasks/evaluate.rs

@@ -11,6 +11,7 @@ use crate::tasks::eval;
 use crate::utils::pastebin::PersistedPastebin;
 use crate::vcs::commit_status::{CommitStatus, CommitStatusError};
 use crate::vcs::generic::{Issue, IssueState, State, VersionControlSystemAPI};
+use crate::vcs::gerrit::http::GerritHTTPApi;
 use crate::vcs::github::compat::GitHubAPI;
 use crate::worker;
 
@@ -21,10 +22,15 @@ use std::time::Instant;
 
 use tracing::{debug_span, error, info, warn};
 
+pub enum SupportedVCS {
+    GitHub(RwLock<GithubAppVendingMachine>),
+    Gerrit,
+}
+
 pub struct EvaluationWorker<E> {
     cloner: checkout::CachedCloner,
     nix: nix::Nix,
-    github_vend: RwLock<GithubAppVendingMachine>,
+    vcs: SupportedVCS,
     acl: Acl,
     identity: String,
     events: E,
@@ -35,7 +41,7 @@ impl<E: stats::SysEvents> EvaluationWorker<E> {
     pub fn new(
         cloner: checkout::CachedCloner,
         nix: &nix::Nix,
-        github_vend: GithubAppVendingMachine,
+        vcs: SupportedVCS,
         acl: Acl,
         identity: String,
         events: E,
@@ -43,7 +49,7 @@ impl<E: stats::SysEvents> EvaluationWorker<E> {
         EvaluationWorker {
             cloner,
             nix: nix.without_limited_supported_systems(),
-            github_vend: RwLock::new(github_vend),
+            vcs,
             acl,
             identity,
             events,
@@ -81,20 +87,21 @@ impl<E: stats::SysEvents + 'static> worker::SimpleWorker for EvaluationWorker<E>
         let span = debug_span!("job", change_id = ?job.change.number);
         let _enter = span.enter();
 
-        // TODO: introduce dynamic dispatcher instantiation here for the VCS API.
-        let mut vending_machine = self
-            .github_vend
-            .write()
-            .expect("Failed to get write lock on github vending machine");
-
-        let github_client = vending_machine
-            .for_repo(&job.repo.owner, &job.repo.name)
-            .expect("Failed to get a github client token");
-
-        let github_api = Rc::new(GitHubAPI::new(github_client.clone()));
+        let vcs_api: Rc<dyn VersionControlSystemAPI> = match self.vcs {
+            SupportedVCS::GitHub(ref vending_machine) => {
+                let mut vending_machine = vending_machine
+                    .write()
+                    .expect("Failed to get write lock on github vending machine");
+                let github_client = vending_machine
+                    .for_repo(&job.repo.owner, &job.repo.name)
+                    .expect("Failed to get a github client token");
+                Rc::new(GitHubAPI::new(github_client.clone()))
+            }
+            SupportedVCS::Gerrit => Rc::new(GerritHTTPApi),
+        };
 
         OneEval::new(
-            github_api,
+            vcs_api,
             &self.nix,
             &self.acl,
             &mut self.events,

ofborg/src/tasks/status_check_collector.rs

@@ -0,0 +1,46 @@
+use std::path::PathBuf;
+
+use tracing::{debug_span, error};
+
+use crate::worker;
+
+#[derive(Serialize, Deserialize, Debug)]
+enum StatusCheckRPCMessage {
+    ListStatuses,
+    ListChecks,
+}
+
+#[allow(dead_code)]
+struct StatusCheckCollector {
+    db_path: PathBuf,
+}
+
+// RPC API worker
+impl worker::SimpleWorker for StatusCheckCollector {
+    type J = StatusCheckRPCMessage;
+
+    fn msg_to_job(
+        &mut self,
+        _method: &str,
+        _headers: &Option<String>,
+        body: &[u8],
+    ) -> Result<Self::J, String> {
+        match serde_json::from_slice(body) {
+            Ok(e) => Ok(e),
+            Err(e) => {
+                error!(
+                    "Failed to deserialize StatusCheckRPCMessage: {:?}",
+                    String::from_utf8(body.to_vec())
+                );
+                panic!("{:?}", e);
+            }
+        }
+    }
+
+    fn consumer(&mut self, job: &Self::J) -> worker::Actions {
+        let span = debug_span!("command");
+        let _enter = span.enter();
+
+        vec![worker::Action::Ack]
+    }
+}

ofborg/src/vcs/gerrit/data_structures.rs

@@ -4,50 +4,65 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Account {
-    pub name: Option<String>,       // User's full name, if configured
-    pub email: Option<String>,      // User's preferred email address
-    pub username: Option<String>,   // User's username, if configured
+    pub name: Option<String>,     // User's full name, if configured
+    pub email: Option<String>,    // User's preferred email address
+    pub username: Option<String>, // User's username, if configured
+}
+
+impl From<Vec<Account>> for crate::vcs::generic::ChangeReviewers {
+    fn from(value: Vec<Account>) -> Self {
+        // FIXME: I don't think Gerrit remembers when we added a group instead of entities.
+        crate::vcs::generic::ChangeReviewers {
+            entity_reviewers: value
+                .into_iter()
+                // FIXME: this is a… quite the assumption, let's relax it by having at _least_ one
+                // identity identifier.
+                .map(|a| a.username.expect("Expected username"))
+                .collect(),
+            team_reviewers: vec![],
+        }
+    }
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Approval {
-    pub r#type: String,                   // Internal name of the approval
-    pub description: String,              // Human-readable category of the approval
-    pub value: i32,                       // Value assigned by the approval (usually a numerical score)
+    pub r#type: String,      // Internal name of the approval
+    pub description: String, // Human-readable category of the approval
+    pub value: i32,          // Value assigned by the approval (usually a numerical score)
     #[serde(rename = "oldValue")]
-    pub old_value: Option<i32>,           // Previous approval score, if present
+    pub old_value: Option<i32>, // Previous approval score, if present
     #[serde(rename = "grantedOn")]
-    pub granted_on: u64,                  // Time in seconds since the UNIX epoch
-    pub by: Account,                      // Reviewer of the patch set
+    pub granted_on: u64, // Time in seconds since the UNIX epoch
+    pub by: Account,         // Reviewer of the patch set
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(rename_all = "UPPERCASE")]
 pub enum ChangeType {
-    Added,        // The file is being created/introduced by this patch
-    Modified,     // The file already exists and has updated content
-    Deleted,      // The file existed, but is being removed by this patch
-    Renamed,      // The file is renamed
-    Copied,       // The file is copied from another file
-    Rewrite,      // The file was rewritten
+    Added,    // The file is being created/introduced by this patch
+    Modified, // The file already exists and has updated content
+    Deleted,  // The file existed, but is being removed by this patch
+    Renamed,  // The file is renamed
+    Copied,   // The file is copied from another file
+    Rewrite,  // The file was rewritten
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct PatchFile {
-    pub file: String,                // Name of the file, or new name if renamed
+    pub file: String, // Name of the file, or new name if renamed
     #[serde(rename = "fileOld")]
-    pub file_old: Option<String>,    // Old name of the file, if renamed
-    pub r#type: ChangeType,              // Type of change (ADDED, MODIFIED, DELETED, etc.)
-    pub insertions: i64,             // Number of insertions in the patch
-    pub deletions: i64,              // Number of deletions in the patch
+    pub file_old: Option<String>, // Old name of the file, if renamed
+    pub r#type: ChangeType, // Type of change (ADDED, MODIFIED, DELETED, etc.)
+    pub insertions: i64, // Number of insertions in the patch
+    pub deletions: i64, // Number of deletions in the patch
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct PatchSetComment {
-    pub file: String,                // Name of the file on which the comment was added
-    pub line: u64,                   // Line number at which the comment was added
-    pub reviewer: Account,           // Account that added the comment
-    pub message: String,             // Comment text
+    pub file: String,      // Name of the file on which the comment was added
+    pub line: u64,         // Line number at which the comment was added
+    pub reviewer: Account, // Account that added the comment
+    pub message: String,   // Comment text
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -63,30 +78,30 @@ pub enum Kind {
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct PatchSet {
-    pub number: u64,                          // Patchset number
-    pub revision: String,                     // Git commit for this patchset
-    pub parents: Vec<String>,                 // List of parent revisions
-    pub r#ref: String,                        // Git reference pointing at the revision
-    pub uploader: Account,                    // Uploader of the patchset
-    pub author: Account,                      // Author of the patchset
+    pub number: u64,          // Patchset number
+    pub revision: String,     // Git commit for this patchset
+    pub parents: Vec<String>, // List of parent revisions
+    pub r#ref: String,        // Git reference pointing at the revision
+    pub uploader: Account,    // Uploader of the patchset
+    pub author: Account,      // Author of the patchset
     #[serde(rename = "createdOn")]
-    pub created_on: u64,                      // Time in seconds since the UNIX epoch
-    pub kind: Kind,                           // Kind of change ("REWORK", "TRIVIAL_REBASE", etc.)
-    pub approvals: Vec<Approval>,             // Approvals granted
-    pub comments: Vec<PatchSetComment>,       // All comments for this patchset
-    pub files: Vec<String>,                   // All changed files in this patchset
+    pub created_on: u64, // Time in seconds since the UNIX epoch
+    pub kind: Kind,           // Kind of change ("REWORK", "TRIVIAL_REBASE", etc.)
+    pub approvals: Vec<Approval>, // Approvals granted
+    pub comments: Vec<PatchSetComment>, // All comments for this patchset
+    pub files: Vec<String>,   // All changed files in this patchset
     #[serde(rename = "sizeInsertions")]
-    pub size_insertions: i64,                 // Size of insertions
+    pub size_insertions: i64, // Size of insertions
     #[serde(rename = "sizeDeletions")]
-    pub size_deletions: i64,                  // Size of deletions
+    pub size_deletions: i64, // Size of deletions
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct ReviewerMessage {
     #[serde(rename = "message")]
-    pub comment_text: String,        // Comment text added by the reviewer
-    pub timestamp: u64,              // Time in seconds since the UNIX epoch when this comment was added
-    pub reviewer: Account,           // Account of the reviewer who added the comment
+    pub comment_text: String, // Comment text added by the reviewer
+    pub timestamp: u64, // Time in seconds since the UNIX epoch when this comment was added
+    pub reviewer: Account, // Account of the reviewer who added the comment
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -97,10 +112,10 @@ pub struct TrackingId {
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct ChangeDependency {
-    pub id: String,                // Change identifier
-    pub number: u64,               // Change number
-    pub revision: String,           // Patchset revision
-    pub r#ref: String,             // Ref name
+    pub id: String,       // Change identifier
+    pub number: u64,      // Change number
+    pub revision: String, // Patchset revision
+    pub r#ref: String,    // Ref name
     #[serde(rename = "isCurrentPatchSet")]
     pub is_current_patch_set: bool, // If the revision is the current patchset of the change
 }
@@ -108,49 +123,49 @@ pub struct ChangeDependency {
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(rename_all = "UPPERCASE")]
 pub enum ChangeStatus {
-    New,        // Change is still being reviewed
-    Merged,     // Change has been merged to its branch
-    Abandoned,  // Change was abandoned by its owner or administrator
+    New,       // Change is still being reviewed
+    Merged,    // Change has been merged to its branch
+    Abandoned, // Change was abandoned by its owner or administrator
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(rename_all = "UPPERCASE")]
 pub enum SubmitStatus {
-    Ok,         // The change is ready for submission or already submitted
-    NotReady,   // The change is missing a required label
-    RuleError,  // An internal server error occurred preventing computation
+    Ok,        // The change is ready for submission or already submitted
+    NotReady,  // The change is missing a required label
+    RuleError, // An internal server error occurred preventing computation
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Label {
-    pub label: String,               // Name of the label
-    pub status: LabelStatus,         // Status of the label
-    pub by: Account,                 // The account that applied the label
+    pub label: String,       // Name of the label
+    pub status: LabelStatus, // Status of the label
+    pub by: Account,         // The account that applied the label
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(rename_all = "UPPERCASE")]
 pub enum LabelStatus {
-    Ok,            // This label provides what is necessary for submission
-    Reject,        // This label prevents the change from being submitted
-    Need,         // The label is required for submission but has not been satisfied
-    May,          // The label may be set but isn’t necessary for submission
-    Impossible,   // The label is required but impossible to complete
+    Ok,         // This label provides what is necessary for submission
+    Reject,     // This label prevents the change from being submitted
+    Need,       // The label is required for submission but has not been satisfied
+    May,        // The label may be set but isn’t necessary for submission
+    Impossible, // The label is required but impossible to complete
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Requirement {
     #[serde(rename = "fallbackText")]
-    pub fallback_text: String,       // Human-readable description of the requirement
-    pub r#type: String,              // Alphanumerical string identifying the requirement
+    pub fallback_text: String, // Human-readable description of the requirement
+    pub r#type: String, // Alphanumerical string identifying the requirement
     pub data: Option<HashMap<String, String>>, // Additional key-value data linked to this requirement
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct SubmitRecord {
-    pub status: SubmitStatus,                   // Current submit status
-    pub labels: Option<Vec<Label>>,             // State of each code review label attribute
-    pub requirements: Vec<Requirement>,         // Requirements for submission
+    pub status: SubmitStatus,           // Current submit status
+    pub labels: Option<Vec<Label>>,     // State of each code review label attribute
+    pub requirements: Vec<Requirement>, // Requirements for submission
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -173,7 +188,7 @@ pub struct Change {
     pub open: bool,
     pub status: ChangeStatus, // "NEW", "MERGED", or "ABANDONED"
     pub private: bool,
-    pub wip: bool, // Work in progress
+    pub wip: bool,                      // Work in progress
     pub comments: Vec<ReviewerMessage>, // Inline/file comments
     #[serde(rename = "trackingIds")]
     pub tracking_ids: Vec<TrackingId>, // Links to issue tracking systems
@@ -191,14 +206,26 @@ pub struct Change {
     pub all_reviewers: Vec<Account>, // List of all reviewers
 }
 
+impl From<Change> for crate::message::Change {
+    fn from(value: Change) -> Self {
+        Self {
+            target_branch: Some(value.branch),
+            // While the change number is deprecated, we actually need it.
+            // FIXME: enforce type level checking of this.
+            number: value.change_number.unwrap(),
+            head_sha: value.current_patch_set.revision,
+        }
+    }
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 pub struct RefUpdate {
     #[serde(rename = "oldRev")]
-    pub old_rev: String,        // The old value of the ref, prior to the update
+    pub old_rev: String, // The old value of the ref, prior to the update
     #[serde(rename = "newRev")]
-    pub new_rev: String,        // The new value the ref was updated to
-    pub ref_name: String,       // Full ref name within the project
-    pub project: String,        // Project path in Gerrit
+    pub new_rev: String, // The new value the ref was updated to
+    pub ref_name: String, // Full ref name within the project
+    pub project: String,  // Project path in Gerrit
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -209,25 +236,25 @@ pub enum GerritStreamEvent {
         patch_set: PatchSet,
         abandoner: Account,
         reason: String,
-        event_created_on: u64
+        event_created_on: u64,
     },
     ChangeDeleted {
         change: Change,
-        deleter: Account
+        deleter: Account,
     },
     ChangeMerged {
         change: Change,
         patch_set: PatchSet,
         submitter: Account,
         new_rev: String,
-        event_created_on: u64
+        event_created_on: u64,
     },
     ChangeRestored {
         change: Change,
         patch_set: PatchSet,
         restorer: Account,
         reason: String,
-        event_created_on: u64
+        event_created_on: u64,
     },
     CommentAdded {
         change: Change,
@@ -235,7 +262,7 @@ pub enum GerritStreamEvent {
         author: Account,
         approvals: Vec<Approval>,
         comment: String,
-        event_created_on: u64
+        event_created_on: u64,
     },
     DroppedOutput,
     HashtagsChanged {
@@ -249,30 +276,30 @@ pub enum GerritStreamEvent {
     ProjectCreated {
         project_name: String,
         project_head: String,
-        event_created_on: u64
+        event_created_on: u64,
     },
     PatchSetCreated {
         change: Change,
         patch_set: PatchSet,
         uploader: Account,
-        event_created_on: u64
+        event_created_on: u64,
     },
     RefUpdated {
         submitter: Account,
         ref_update: RefUpdate,
-        event_created_on: u64
+        event_created_on: u64,
     },
     BatchRefUpdated {
         submitter: Account,
         ref_updates: Vec<RefUpdate>,
-        event_created_on: u64
+        event_created_on: u64,
     },
     ReviewerAdded {
         change: Change,
         patch_set: PatchSet,
         reviewer: Account,
         adder: Account,
-        event_created_on: u64
+        event_created_on: u64,
     },
     ReviewerDeleted {
         change: Change,
@@ -288,19 +315,19 @@ pub enum GerritStreamEvent {
         old_topic: Option<String>,
         new_topic: Option<String>,
         changer: Account,
-        event_created_on: u64
+        event_created_on: u64,
     },
     WorkInProgressStateChanged {
         change: Change,
         patch_set: PatchSet,
         changer: Account,
-        event_created_on: u64
+        event_created_on: u64,
     },
     PrivateStateChanged {
         change: Change,
         patch_set: PatchSet,
         changer: Account,
-        event_created_on: u64
+        event_created_on: u64,
     },
     VoteDeleted {
         change: Change,
@@ -313,6 +340,6 @@ pub enum GerritStreamEvent {
     ProjectHeadUpdate {
         old_head: String,
         new_head: String,
-        event_created_on: u64
-    }
+        event_created_on: u64,
+    },
 }

ofborg/src/vcs/gerrit/http.rs

@@ -0,0 +1,49 @@
+//! REST API bindings for Gerrit
+//! TODO:
+//! - trace IDs support
+//! - label support
+
+use super::data_structures::{Account, Change};
+
+pub struct GerritHTTPApi;
+
+impl GerritHTTPApi {
+    // async fn get_project(&self, project_name: &str) -> Project {}
+    /// Fetches all changes according to the query and the given limit.
+    /// This will default to 60 changes by default.
+    pub(crate) async fn list_changes(&self, _query: &str, _limit: Option<u64>) -> Vec<Change> {
+        Default::default()
+    }
+
+    /// Fetch the latest change ID for a given project and CL number.
+    pub(crate) async fn get_change_id(&self, _project_name: &str, _cl_number: u64) -> String {
+        "".to_owned()
+    }
+
+    /// Fetch a given change according to the change ID (not the CL number).
+    pub(crate) async fn get_change(&self, _change_id: &str) -> Option<Change> {
+        Default::default()
+    }
+
+    /// Set additional and remove certain hashtags for a given change ID (not the CL number).
+    pub(crate) async fn set_hashtags(
+        &self,
+        _change_id: &str,
+        _add: &[String],
+        _remove: &[String],
+    ) -> Vec<String> {
+        Default::default()
+    }
+    /// List all reviewers on a given change ID (not the CL number).
+    pub(crate) async fn list_reviewers(&self, _change_id: &str) -> Vec<Account> {
+        Default::default()
+    }
+    /// Set reviewers and a message on a given change ID (not the CL number).
+    pub(crate) async fn set_reviewers(
+        &self,
+        _change_id: &str,
+        _message: &str,
+        _reviewers: Vec<Account>,
+    ) {
+    }
+}

ofborg/src/vcs/gerrit/impl.rs

@@ -0,0 +1,137 @@
+//! Implementation of the VCS API for Gerrit
+//! This uses the HTTP API.
+
+use futures_util::FutureExt;
+
+use crate::vcs::generic::VersionControlSystemAPI;
+
+use super::{data_structures::Account, http::GerritHTTPApi};
+
+impl VersionControlSystemAPI for GerritHTTPApi {
+    // The next three APIs are todo!() because they cannot be implemented in Gerrit.
+    // Gerrit does not offer any way to get this information out.
+    // GerritHTTPApi needs to return something like Unsupported
+    // and we need to compose a GerritHTTPApi with a GerritForge which contains an implementation
+    // of check statuses and commit statuses and an issue tracker.
+    fn create_check_statuses(
+        &self,
+        _repo: &crate::message::Repo,
+        _checks: Vec<crate::vcs::generic::CheckRunOptions>,
+    ) -> futures_util::future::BoxFuture<()> {
+        todo!();
+    }
+
+    fn create_commit_statuses(
+        &self,
+        _repo: &crate::message::Repo,
+        _sha: String,
+        _state: crate::vcs::generic::State,
+        _context: String,
+        _description: String,
+        _target_url: String,
+    ) -> futures_util::future::BoxFuture<Result<(), crate::vcs::commit_status::CommitStatusError>>
+    {
+        todo!();
+    }
+
+    fn get_issue(
+        &self,
+        _repo: &crate::message::Repo,
+        _number: u64,
+    ) -> futures_util::future::BoxFuture<Result<crate::vcs::generic::Issue, String>> {
+        todo!();
+    }
+
+    fn get_repository(&self, _repo: &crate::message::Repo) -> crate::vcs::generic::Repository {
+        todo!();
+    }
+
+    fn get_changes(
+        &self,
+        repo: &crate::message::Repo,
+    ) -> futures_util::future::BoxFuture<Vec<crate::message::Change>> {
+        let repo_name = repo.name.to_owned();
+        async move {
+            self.list_changes(&format!("project:{}", &repo_name), None)
+                .await
+                .into_iter()
+                .map(|c| c.into())
+                .collect()
+        }
+        .boxed()
+    }
+
+    fn get_change(
+        &self,
+        repo: &crate::message::Repo,
+        number: u64,
+    ) -> futures_util::future::BoxFuture<Option<crate::message::Change>> {
+        let repo_name = repo.name.to_owned();
+        async move {
+            let change_id = self.get_change_id(&repo_name, number).await;
+            GerritHTTPApi::get_change(&self, &change_id)
+                .await
+                .map(|c| c.into())
+        }
+        .boxed()
+    }
+
+    fn update_labels(
+        &self,
+        repo: &crate::message::Repo,
+        number: u64,
+        add: &[String],
+        remove: &[String],
+    ) -> futures_util::future::BoxFuture<()> {
+        let add = add.to_owned();
+        let remove = remove.to_owned();
+        let repo_name = repo.name.to_owned();
+
+        async move {
+            let change_id = self.get_change_id(&repo_name, number).await;
+            self.set_hashtags(&change_id, &add, &remove).await;
+        }
+        .boxed()
+    }
+
+    fn get_existing_reviewers(
+        &self,
+        repo: &crate::message::Repo,
+        number: u64,
+    ) -> futures_util::future::BoxFuture<crate::vcs::generic::ChangeReviewers> {
+        let repo_name = repo.name.to_owned();
+        async move {
+            let change_id = self.get_change_id(&repo_name, number).await;
+            self.list_reviewers(&change_id).await.into()
+        }
+        .boxed()
+    }
+
+    fn request_reviewers(
+        &self,
+        repo: &crate::message::Repo,
+        number: u64,
+        entity_reviewers: Vec<String>,
+        // FIXME: support group reviews
+        _team_reviewers: Vec<String>,
+    ) -> futures_util::future::BoxFuture<()> {
+        let repo_name = repo.name.to_owned();
+        async move {
+            let change_id = self.get_change_id(&repo_name, number).await;
+            self.set_reviewers(
+                &change_id,
+                "Automatic reviewer request",
+                entity_reviewers
+                    .into_iter()
+                    .map(|reviewer| Account {
+                        username: Some(reviewer),
+                        email: None,
+                        name: None,
+                    })
+                    .collect(),
+            )
+            .await
+        }
+        .boxed()
+    }
+}

ofborg/src/vcs/gerrit/mod.rs

@@ -1,3 +1,5 @@
 pub mod checks;
 pub mod data_structures;
+pub mod http;
+pub mod r#impl;
 // pub mod events;