afterhours-shift-manager/terraform/iam_github_deploy.tf

# GitHub Actions OIDC role for .github/workflows/deploy.yaml and deploy-api.yaml.
#
# One role: GitHub Environments have a single DEPLOY_ROLE_ARN. Trust is pinned
# to Environments dev and prod (immutable and classic subject forms) and
# job_workflow_ref to deploy.yaml at main plus deploy-api.yaml at main and v*.

data "aws_iam_policy_document" "github_deploy_assume" {
  statement {
    sid     = "GithubDeployOidc"
    effect  = "Allow"
    actions = ["sts:AssumeRoleWithWebIdentity"]

    principals {
      type        = "Federated"
      identifiers = [local.github_oidc_provider_arn]
    }

    condition {
      test     = "StringEquals"
      variable = "token.actions.githubusercontent.com:aud"
      values   = ["sts.amazonaws.com"]
    }

    condition {
      test     = "StringEquals"
      variable = "token.actions.githubusercontent.com:sub"
      values   = local.github_oidc_subs
    }

    condition {
      test     = "StringLike"
      variable = "token.actions.githubusercontent.com:job_workflow_ref"
      values = [
        "${var.github_repo}/.github/workflows/deploy.yaml@refs/heads/${var.github_deploy_branch}",
        "${var.github_repo}/.github/workflows/deploy-api.yaml@refs/heads/${var.github_deploy_branch}",
        "${var.github_repo}/.github/workflows/deploy-api.yaml@refs/tags/v*",
      ]
    }
  }
}

resource "aws_iam_role" "github_deploy" {
  name                 = local.deploy_role
  path                 = "/tf-managed/"
  description          = "GitHub Actions zip and image deploy role for ${var.github_repo}"
  assume_role_policy   = data.aws_iam_policy_document.github_deploy_assume.json
  max_session_duration = 3600
}

data "aws_iam_policy_document" "github_deploy" {
  statement {
    sid    = "ListArtifactsBucket"
    effect = "Allow"
    actions = [
      "s3:GetBucketLocation",
      "s3:ListBucket",
    ]
    resources = [aws_s3_bucket.artifacts.arn]
  }

  statement {
    sid    = "UploadFunctionArtifacts"
    effect = "Allow"
    actions = [
      "s3:GetObject",
      "s3:PutObject",
    ]
    resources = ["${aws_s3_bucket.artifacts.arn}/functions/*"]
  }

  statement {
    sid    = "UpdateFunctionCode"
    effect = "Allow"
    actions = [
      "lambda:GetFunction",
      "lambda:GetFunctionConfiguration",
      "lambda:UpdateFunctionCode",
    ]
    resources = [for fn in local.functions : "arn:aws:lambda:${var.aws_region}:${local.account_id}:function:${fn.function_name}"]
  }

  statement {
    sid    = "EcrAuth"
    effect = "Allow"
    actions = [
      "ecr:GetAuthorizationToken",
    ]
    resources = ["*"]
  }

  statement {
    sid    = "EcrPush"
    effect = "Allow"
    actions = [
      "ecr:BatchCheckLayerAvailability",
      "ecr:BatchGetImage",
      "ecr:CompleteLayerUpload",
      "ecr:GetDownloadUrlForLayer",
      "ecr:InitiateLayerUpload",
      "ecr:PutImage",
      "ecr:UploadLayerPart",
      "ecr:DescribeRepositories",
      "ecr:DescribeImages",
    ]
    resources = [aws_ecr_repository.api.arn]
  }

  statement {
    sid    = "EcsDeploy"
    effect = "Allow"
    actions = [
      "ecs:DescribeServices",
      "ecs:DescribeTaskDefinition",
      "ecs:DescribeTasks",
      "ecs:RegisterTaskDefinition",
      "ecs:UpdateService",
    ]
    resources = ["*"]
  }

  statement {
    sid     = "PassTaskRoles"
    effect  = "Allow"
    actions = ["iam:PassRole"]
    resources = [
      aws_iam_role.ecs_task.arn,
      aws_iam_role.ecs_execution.arn,
    ]
  }

  statement {
    sid    = "DeployParams"
    effect = "Allow"
    actions = [
      "ssm:GetParameter",
    ]
    resources = [
      "arn:aws:ssm:${var.aws_region}:${local.account_id}:parameter${local.ssm_prefix}/deploy/*",
    ]
  }
}

resource "aws_iam_role_policy" "github_deploy" {
  name   = "afterhours-shift-manager-deploy"
  role   = aws_iam_role.github_deploy.id
  policy = data.aws_iam_policy_document.github_deploy.json
}