expose custom env vars for run step runner for custom steps

runatlantis.io/docs/atlantis-yaml-reference.md

@@ -180,6 +180,13 @@ Or a custom command
 * `PLANFILE` - Absolute path to the location where Atlantis expects the plan to
 either be generated (by plan) or already exist (if running apply). Can be used to
 override the built-in `plan`/`apply` commands, ex. `run: terraform plan -out $PLANFILE`.
+* `BASE_REPO_NAME` - Name of the repository that the pull request will be merged into, ex. `atlantis`.
+* `BASE_REPO_OWNER` - Owner of the repository that the pull request will be merged into, ex. `runatlantis`.
+* `HEAD_REPO_NAME` - Name of the repository that is getting merged into the base repository, ex. `atlantis`.
+* `HEAD_REPO_OWNER` - Owner of the repository that is getting merged into the base repository, ex. `acme-corp`.
+* `HEAD_BRANCH_NAME` - Name of the head branch of the pull request
+* `PULL_NUM` - Pull request number or ID, ex. `2`.
+* `PULL_AUTHOR` - Username of the pull request author, ex. `acme-user`.
 :::
 
 ## Next Steps

server/events/runtime/run_step_runner.go

@@ -29,13 +29,24 @@ func (r *RunStepRunner) Run(ctx models.ProjectCommandContext, command []string,
 		tfVersion = ctx.ProjectConfig.TerraformVersion.String()
 	}
 	baseEnvVars := os.Environ()
-	customEnvVars := []string{
-		fmt.Sprintf("WORKSPACE=%s", ctx.Workspace),
-		fmt.Sprintf("ATLANTIS_TERRAFORM_VERSION=%s", tfVersion),
-		fmt.Sprintf("DIR=%s", path),
-		fmt.Sprintf("PLANFILE=%s", filepath.Join(path, GetPlanFilename(ctx.Workspace, ctx.ProjectConfig))),
+	customEnvVars := map[string]string{
+		"WORKSPACE":                  ctx.Workspace,
+		"ATLANTIS_TERRAFORM_VERSION": tfVersion,
+		"DIR":              path,
+		"PLANFILE":         filepath.Join(path, GetPlanFilename(ctx.Workspace, ctx.ProjectConfig)),
+		"BASE_REPO_NAME":   ctx.BaseRepo.Name,
+		"BASE_REPO_OWNER":  ctx.BaseRepo.Owner,
+		"HEAD_REPO_NAME":   ctx.HeadRepo.Name,
+		"HEAD_REPO_OWNER":  ctx.HeadRepo.Owner,
+		"HEAD_BRANCH_NAME": ctx.Pull.Branch,
+		"PULL_NUM":         fmt.Sprintf("%d", ctx.Pull.Num),
+		"PULL_AUTHOR":      ctx.Pull.Author,
+	}
+
+	finalEnvVars := baseEnvVars
+	for key, val := range customEnvVars {
+		finalEnvVars = append(finalEnvVars, fmt.Sprintf("%s=%s", key, val))
 	}
-	finalEnvVars := append(baseEnvVars, customEnvVars...)
 	cmd.Env = finalEnvVars
 	out, err := cmd.CombinedOutput()
 

server/events/runtime/run_step_runner_test.go

@@ -38,6 +38,10 @@ func TestRunStepRunner_Run(t *testing.T) {
 			Command: "echo workspace=$WORKSPACE version=$ATLANTIS_TERRAFORM_VERSION dir=$DIR planfile=$PLANFILE",
 			ExpOut:  "workspace=myworkspace version=0.11.0 dir=$DIR planfile=$DIR/myworkspace.tfplan\n",
 		},
+		{
+			Command: "echo base_repo_name=$BASE_REPO_NAME base_repo_owner=$BASE_REPO_OWNER head_repo_name=$HEAD_REPO_NAME head_repo_owner=$HEAD_REPO_OWNER head_branch_name=$HEAD_BRANCH_NAME pull_num=$PULL_NUM pull_author=$PULL_AUTHOR",
+			ExpOut:  "base_repo_name=atlantis base_repo_owner=runatlantis head_repo_name=atlantis head_repo_owner=runatlantis head_branch_name=add-feat pull_num=2 pull_author=acme\n",
+		},
 	}
 
 	projVersion, err := version.NewVersion("v0.11.0")
@@ -47,6 +51,19 @@ func TestRunStepRunner_Run(t *testing.T) {
 		DefaultTFVersion: defaultVersion,
 	}
 	ctx := models.ProjectCommandContext{
+		BaseRepo: models.Repo{
+			Name:  "atlantis",
+			Owner: "runatlantis",
+		},
+		HeadRepo: models.Repo{
+			Name:  "atlantis",
+			Owner: "runatlantis",
+		},
+		Pull: models.PullRequest{
+			Num:    2,
+			Branch: "add-feat",
+			Author: "acme",
+		},
 		Log:        logging.NewNoopLogger(),
 		Workspace:  "myworkspace",
 		RepoRelDir: "mydir",