From accb4c915ee510e02809bbd6b7de3dbca77b0217 Mon Sep 17 00:00:00 2001
From: leigh capili <leigh@null.net>
Date: Wed, 3 Mar 2021 08:38:00 -0700
Subject: [PATCH] Improve SOPS GPG guide key management

- Switch to batch GPG key creation
- Accurately name the cluster's decryption key
- Suggest password-manager backup
- Optionally cleanup secret key from generating machine
- Optionally commit the public key to the repo for team members
- Document SOPS limitations decryption required for editing / appending fields

Signed-off-by: leigh capili <leigh@null.net>
---
 docs/guides/mozilla-sops.md | 152 ++++++++++++++++++++++++++----------
 1 file changed, 110 insertions(+), 42 deletions(-)

diff --git a/docs/guides/mozilla-sops.md b/docs/guides/mozilla-sops.md
index 4ff88850..1554fee1 100644
--- a/docs/guides/mozilla-sops.md
+++ b/docs/guides/mozilla-sops.md
@@ -19,24 +19,30 @@ brew install gnupg sops
 
 ## Generate a GPG key
 
-Generate a GPG key with OpenPGP without specifying a passphrase:
+Generate a GPG/OpenPGP key with no passphrase (`%no-protection`):
 
 ```console
-$ gpg --full-generate-key
-
-Real name: stefanprodan
-Email address: stefanprodan@users.noreply.github.com
-Comment:
-You selected this USER-ID:
-    "stefanprodan <stefanprodan@users.noreply.github.com>"
+gpg --batch --full-generate-key <<EOF
+%no-protection
+Key-Type: 1
+Key-Length: 4096
+Subkey-Type: 1
+Subkey-Length: 4096
+Expire-Date: 0
+Name-Comment: flux secrets
+Name-Real: cluster0.yourdomain.com
+EOF
 ```
 
-Retrieve the GPG key ID (second row of the sec column):
+The above configuration creates an rsa4096 key that does not expire.
+For a full list of options to consider for your environment, see [Unattended GPG key generation](https://www.gnupg.org/documentation/manuals/gnupg/Unattended-GPG-key-generation.html).
+
+Retrieve the GPG key fingerprint (second row of the sec column):
 
 ```console
-$ gpg --list-secret-keys stefanprodan@users.noreply.github.com
+$ gpg --list-secret-keys cluster0.yourdomain.com
 
-sec   rsa3072 2020-09-06 [SC]
+sec   rsa4096 2020-09-06 [SC]
       1F3D1CED2F865F5E59CA564553241F147E7C5FA4
 ```
 
@@ -51,6 +57,98 @@ kubectl create secret generic sops-gpg \
 --from-file=sops.asc=/dev/stdin
 ```
 
+It's a good idea to back up this secret-key/k8s-Secret with a password manager or offline storage.
+Also consider deleting the secret decryption key from you machine:
+
+```console
+gpg --delete-secret-keys 1F3D1CED2F865F5E59CA564553241F147E7C5FA4
+```
+
+## Configure in-cluster secrets decryption
+
+Register the Git repository on your cluster:
+
+```sh
+flux create source git my-secrets \
+--url=https://github.com/my-org/my-secrets
+```
+
+Create a kustomization for reconciling the secrets on the cluster:
+
+```sh
+flux create kustomization my-secrets \
+--source=my-secrets \
+--path=./clusters/cluster0 \
+--prune=true \
+--interval=10m \
+--decryption-provider=sops \
+--decryption-secret=sops-gpg
+```
+
+Note that the `sops-gpg` can contain more than one key, sops will try to decrypt the
+secrets by iterating over all the private keys until it finds one that works.
+
+## Optional: Export the public key into the git directory
+
+Commit the public key to the repository so that team members who clone the repo can encrypt new files:
+
+```console
+gpg --export \
+--armor 1F3D1CED2F865F5E59CA564553241F147E7C5FA4 > ./clusters/cluster0/.sops.pub.asc
+```
+
+Check the file contents to ensure it's the public key before adding it to the repo and committing.
+
+```console
+git add ./clusters/cluster0/.sops.pub.asc
+git commit -am 'Share GPG public key for secrets generation'
+```
+
+Team members can then import this key when they pull the git repository:
+
+```console
+gpg --import ./clusters/cluster0/.sops.pub.asc
+```
+
+!!! hint
+    The public key is sufficient for creating brand new files.
+    The secret key is required for decrypting and editing existing files because SOPS computes a MAC on all values.
+    When using solely the public key to add or remove a field, the whole file should be deleted and recreated.
+
+## Configure the git directory for encryption
+
+Write a [sops config file](https://github.com/mozilla/sops#using-sops-yaml-conf-to-select-kms-pgp-for-new-files) to the specific cluster or namespace directory used
+to store encrypted objects with this particular GPG key's fingerprint.
+
+```yaml
+# ./clusters/cluster0/.sops.yaml
+creation_rules:
+  - path_regex: .*.yaml
+    encrypted_regex: ^(data|stringData)$
+    pgp: 1F3D1CED2F865F5E59CA564553241F147E7C5FA4
+```
+
+This config applies recursively to all sub-directories.
+Multiple directories can use separate sops configs.
+Contributors using the `sops` CLI to create and encrypt files
+won't have to worry about specifying the proper key for the target cluster or namespace.
+
+`encrypted_regex` helps encrypt the the proper `data` and `stringData` fields for Secrets.
+You may wish to add other fields if you are encrypting other types of Objects.
+
+!!! hint
+    Note that you should encrypt only the `data` or `stringData` section. Encrypting the Kubernetes
+    secret metadata, kind or apiVersion is not supported by kustomize-controller.
+
+Ignore all `.sops.yaml` files in a [`.sourceignore`](../components/source/gitrepositories#excluding-files) file at the root of your repo.
+
+```sh
+touch .sourceignore
+echo '**/.sops.yaml' >> .sourceignore
+```
+
+You can now commit your SOPS config.
+
 ## Encrypt secrets
 
 Generate a Kubernetes secret manifest with kubectl:
@@ -66,44 +164,14 @@ kubectl -n default create secret generic basic-auth \
 Encrypt the secret with sops using your GPG key:
 
 ```sh
-sops --encrypt \
---pgp=1F3D1CED2F865F5E59CA564553241F147E7C5FA4 \
---encrypted-regex '^(data|stringData)$' \
---in-place basic-auth.yaml
+sops --encrypt --in-place basic-auth.yaml
 ```
 
-!!! hint
-    Note that you should encrypt only the `data` section. Encrypting the Kubernetes
-    secret metadata, kind or apiVersion is not supported by kustomize-controller.
-
 You can now commit the encrypted secret to your Git repository.
 
 !!! hint
     Note that you shouldn't apply the encrypted secrets onto the cluster with kubectl. SOPS encrypted secrets are designed to be consumed by kustomize-controller.
 
-## Configure secrets decryption
-
-Registry the Git repository on your cluster:
-
-```sh
-flux create source git my-secrets \
---url=https://github.com/my-org/my-secrets
-```
-
-Create a kustomization for reconciling the secrets on the cluster:
-
-```sh
-flux create kustomization my-secrets \
---source=my-secrets \
---prune=true \
---interval=10m \
---decryption-provider=sops \
---decryption-secret=sops-gpg
-```
-
-Note that the `sops-gpg` can contain more than one key, sops will try to decrypt the
-secrets by iterating over all the private keys until it finds one that works.
-
 ### Using various cloud providers
 
 When using AWS/GCP KMS, you don't have to include the gpg `secretRef` under