Made gitlab:repo:push action idempotent.

Signed-off-by: Bogdan Nechyporenko <bnechyporenko@bol.com>

.changeset/good-chairs-visit.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend-module-gitlab': patch
+---
+
+Made gitlab:repo:push action idempotent.

beps/0004-scaffolder-task-idempotency/README.md

@@ -154,30 +154,36 @@ export function createGithubRepoCreateAction(options: {
         username: owner,
       });
 
-      await ctx.checkpoint('repo.creation', async () => {
-        const repoCreationPromise =
-          user.data.type === 'Organization'
-            ? client.rest.repos.createInOrg({
-                name: repo,
-                org: owner,
-              })
-            : client.rest.repos.createForAuthenticatedUser({
-                name: repo,
-              });
-        const { repoUrl } = await repoCreationPromise;
-        return { repoUrl };
+      await ctx.checkpoint({
+        key: 'repo.creation.v1',
+        fn: async () => {
+          const repoCreationPromise =
+            user.data.type === 'Organization'
+              ? client.rest.repos.createInOrg({
+                  name: repo,
+                  org: owner,
+                })
+              : client.rest.repos.createForAuthenticatedUser({
+                  name: repo,
+                });
+          const { repoUrl } = await repoCreationPromise;
+          return { repoUrl };
+        },
       });
 
       if (secrets) {
-        await ctx.checkpoint('repo.create.variables', async () => {
-          for (const [key, value] of Object.entries(repoVariables ?? {})) {
-            await client.rest.actions.createRepoVariable({
-              owner,
-              repo,
-              name: key,
-              value: value,
-            });
-          }
+        await ctx.checkpoint({
+          key: 'repo.create.variables',
+          fn: async () => {
+            for (const [key, value] of Object.entries(repoVariables ?? {})) {
+              await client.rest.actions.createRepoVariable({
+                owner,
+                repo,
+                name: key,
+                value: value,
+              });
+            }
+          },
         });
       }
 
@@ -202,9 +208,12 @@ Checkpoints will allow action authors to create actions where code paths are ign
 This will be provided on a context object and action of author provide a key and a callback.
 
 ```typescript
-await ctx.checkpoint('repo.creation', async () => {
-  const { repoUrl } = await client.rest.Repository.create({});
-  return { repoUrl };
+await ctx.checkpoint({
+  key: 'repo.creation',
+  fn: async () => {
+    const { repoUrl } = await client.rest.Repository.create({});
+    return { repoUrl };
+  },
 });
 ```
 
@@ -259,6 +268,12 @@ Task state will be stored in the extra column `state` in the table `tasks` with
 }
 ```
 
+Whenever you change the return type of the checkpoint, we encourage you to change the ID.
+For example, you can embed the versioning or another indicator for that.
+If you'll preserve the same key, and you'll try to restart the affected task, it will fail on this checkpoint.
+The cached result will not match with the expected updated return type.
+By changing the key, you'll invalidate the cache of the checkpoint.
+
 #### Workspace Persistence
 
 The workspace will be serialized and stored in the database by default. This serialization should occur at the end of a step, and after each checkpoint. It will be possible to provide additional modules to extend the workspace serialization to other providers, such as GCS or S3 instead of the database.

plugins/scaffolder-backend-module-gitlab/src/actions/gitlabRepoPush.ts

@@ -151,19 +151,24 @@ export const createGitlabRepoPushAction = (options: {
         execute_filemode: file.executable,
       }));
 
-      let branchExists = false;
-      try {
-        await api.Branches.show(repoID, branchName);
-        branchExists = true;
-      } catch (e: any) {
-        if (e.cause?.response?.status !== 404) {
-          throw new InputError(
-            `Failed to check status of branch '${branchName}'. Please make sure that branch already exists or Backstage has permissions to create one. ${getErrorMessage(
-              e,
-            )}`,
-          );
-        }
-      }
+      const branchExists = await ctx.checkpoint({
+        key: `branch.exists.${repoID}.${branchName}`,
+        fn: async () => {
+          try {
+            await api.Branches.show(repoID, branchName);
+            return true;
+          } catch (e: any) {
+            if (e.cause?.response?.status !== 404) {
+              throw new InputError(
+                `Failed to check status of branch '${branchName}'. Please make sure that branch already exists or Backstage has permissions to create one. ${getErrorMessage(
+                  e,
+                )}`,
+              );
+            }
+          }
+          return false;
+        },
+      });
 
       if (!branchExists) {
         // create a branch using the default branch as ref
@@ -181,15 +186,22 @@ export const createGitlabRepoPushAction = (options: {
       }
 
       try {
-        const commit = await api.Commits.create(
-          repoID,
-          branchName,
-          ctx.input.commitMessage,
-          actions,
-        );
+        const commitId = await ctx.checkpoint({
+          key: `commit.create.${repoID}.${branchName}`,
+          fn: async () => {
+            const commit = await api.Commits.create(
+              repoID,
+              branchName,
+              ctx.input.commitMessage,
+              actions,
+            );
+            return commit.id;
+          },
+        });
+
         ctx.output('projectid', repoID);
         ctx.output('projectPath', repoID);
-        ctx.output('commitHash', commit.id);
+        ctx.output('commitHash', commitId);
       } catch (e) {
         throw new InputError(
           `Committing the changes to ${branchName} failed. Please check that none of the files created by the template already exists. ${getErrorMessage(