diff --git a/.github/workflows/release-artifacts.yml b/.github/workflows/release-artifacts.yml
new file mode 100644
index 0000000000..f292d703ed
--- /dev/null
+++ b/.github/workflows/release-artifacts.yml
@@ -0,0 +1,90 @@
+# GitHub actions workflow which builds the release artifacts.
+
+name: Build release artifacts
+
+on:
+  push:
+    # we build on develop and release branches to (hopefully) get early warning
+    # of things breaking
+    branches: ["develop", "release-*"]
+
+    # we also rebuild on tags, so that we can be sure of picking the artifacts
+    # from the right tag.
+    tags: ["v*"]
+
+permissions:
+  contents: write
+
+jobs:
+  # first get the list of distros to build for.
+  get-distros:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - id: set-distros
+        run: |
+          echo "::set-output name=distros::$(scripts-dev/build_debian_packages --show-dists-json)"
+    # map the step outputs to job outputs
+    outputs:
+      distros: ${{ steps.set-distros.outputs.distros }}
+
+  # now build the packages with a matrix build.
+  build-debs:
+    needs: get-distros
+    name: "Build .deb packages"
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        distro: ${{ fromJson(needs.get-distros.outputs.distros) }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          path: src
+      - uses: actions/setup-python@v2
+      - run: ./src/scripts-dev/build_debian_packages "${{ matrix.distro }}"
+      - uses: actions/upload-artifact@v2
+        with:
+          name: debs
+          path: debs/*
+
+  build-sdist:
+    name: "Build pypi distribution files"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - run: pip install wheel
+      - run: |
+          python setup.py sdist bdist_wheel
+      - uses: actions/upload-artifact@v2
+        with:
+          name: python-dist
+          path: dist/*
+
+  # if it's a tag, create a release and attach the artifacts to it
+  attach-assets:
+    name: "Attach assets to release"
+    if: startsWith(github.ref, 'refs/tags/')
+    needs:
+      - build-debs
+      - build-sdist
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download all workflow run artifacts
+        uses: actions/download-artifact@v2
+      - name: Build a tarball for the debs
+        run: tar -cvJf debs.tar.xz debs
+      - name: Attach to release
+        uses: softprops/action-gh-release@a929a66f232c1b11af63782948aa2210f981808a  # PR#109
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          files: |
+            python-dist/*
+            debs.tar.xz
+          # if it's not already published, keep the release as a draft.
+          draft: true
+          # mark it as a prerelease if the tag contains 'rc'.
+          prerelease: ${{ contains(github.ref, 'rc') }}
diff --git a/CHANGES.md b/CHANGES.md
index a1419d6495..82baaa2d1f 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,20 @@
+Synapse 1.38.0 (2021-07-13)
+===========================
+
+This release includes a database schema update which could result in elevated disk usage. See the [upgrade notes](https://matrix-org.github.io/synapse/develop/upgrade#upgrading-to-v1380) for more information.
+
+No significant changes since 1.38.0rc3.
+
+
+Synapse 1.38.0rc3 (2021-07-13)
+==============================
+
+Internal Changes
+----------------
+
+- Build the Debian packages in CI. ([\#10247](https://github.com/matrix-org/synapse/issues/10247), [\#10379](https://github.com/matrix-org/synapse/issues/10379))
+
+
 Synapse 1.38.0rc2 (2021-07-09)
 ==============================
 
@@ -17,8 +34,6 @@ Improved Documentation
 Synapse 1.38.0rc1 (2021-07-06)
 ==============================
 
-This release includes a database schema update which could result in elevated disk usage. See the [upgrade notes](https://matrix-org.github.io/synapse/develop/upgrade#upgrading-to-v1380) for more information.
-
 Features
 --------
 
diff --git a/debian/changelog b/debian/changelog
index cafd03c6c1..43d26fc133 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,8 +1,18 @@
-matrix-synapse-py3 (1.37.1ubuntu1) UNRELEASED; urgency=medium
+matrix-synapse-py3 (1.38.0) stable; urgency=medium
 
+  * New synapse release 1.38.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 13 Jul 2021 13:20:56 +0100
+
+matrix-synapse-py3 (1.38.0rc3) prerelease; urgency=medium
+
+  [ Erik Johnston ]
   * Add synapse_review_recent_signups script
 
- -- Erik Johnston <erikj@matrix.org>  Thu, 01 Jul 2021 15:55:03 +0100
+  [ Synapse Packaging team ]
+  * New synapse release 1.38.0rc3.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 13 Jul 2021 11:53:56 +0100
 
 matrix-synapse-py3 (1.37.1) stable; urgency=medium
 
diff --git a/scripts-dev/build_debian_packages b/scripts-dev/build_debian_packages
index 546724f89f..e25c5bb265 100755
--- a/scripts-dev/build_debian_packages
+++ b/scripts-dev/build_debian_packages
@@ -10,6 +10,7 @@
 # can be passed on the commandline for debugging.
 
 import argparse
+import json
 import os
 import signal
 import subprocess
@@ -34,6 +35,8 @@ By default, builds for all known distributions, but a list of distributions
 can be passed on the commandline for debugging.
 """
 
+projdir = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+
 
 class Builder(object):
     def __init__(self, redirect_stdout=False):
@@ -57,9 +60,6 @@ class Builder(object):
             raise
 
     def _inner_build(self, dist, skip_tests=False):
-        projdir = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
-        os.chdir(projdir)
-
         tag = dist.split(":", 1)[1]
 
         # Make the dir where the debs will live.
@@ -93,6 +93,7 @@ class Builder(object):
             ],
             stdout=stdout,
             stderr=subprocess.STDOUT,
+            cwd=projdir,
         )
 
         container_name = "synapse_build_" + tag
@@ -179,6 +180,11 @@ if __name__ == "__main__":
         action="store_true",
         help="skip running tests after building",
     )
+    parser.add_argument(
+        "--show-dists-json",
+        action="store_true",
+        help="instead of building the packages, just list the dists to build for, as a json array",
+    )
     parser.add_argument(
         "dist",
         nargs="*",
@@ -186,4 +192,7 @@ if __name__ == "__main__":
         help="a list of distributions to build for. Default: %(default)s",
     )
     args = parser.parse_args()
-    run_builds(dists=args.dist, jobs=args.jobs, skip_tests=args.no_check)
+    if args.show_dists_json:
+        print(json.dumps(DISTS))
+    else:
+        run_builds(dists=args.dist, jobs=args.jobs, skip_tests=args.no_check)
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 119afa9ebe..5ecce24eee 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -47,7 +47,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.38.0rc2"
+__version__ = "1.38.0"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     # We import here so that we don't have to install a bunch of deps when