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Posted to notifications@apisix.apache.org by "Neilblaze (via GitHub)" <gi...@apache.org> on 2023/04/10 08:53:06 UTC
[GitHub] [apisix-website] Neilblaze commented on a diff in pull request #1539: blog: Add mTLS everywhere blog post
Neilblaze commented on code in PR #1539:
URL: https://github.com/apache/apisix-website/pull/1539#discussion_r1161556874
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blog/en/blog/2023/03/23/mtls-everywhere.md:
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@@ -0,0 +1,584 @@
+---
+title: mTLS everywhere
+authors:
+ - name: Nicolas Fränkel
+ title: Author
+ url: https://github.com/nfrankel
+ image_url: https://avatars.githubusercontent.com/u/752258
+keywords:
+ - Security
+ - TLS
+ - DevOps
+ - cert-manager
+description: >
+ Security in one's information system has always been among the most critical Non-Functional Requirements. Transport Secure Layer, aka TLS, formerly SSL, is among its many pillars. In this post, I'll show how to configure TLS for Apache APISIX.
+tags: [Ecosystem]
+image: https://blog.frankel.ch/assets/resources/mtls-everywhere/data-key-gcce68039d_large.jpg
+---
+
+>Security in one's information system has always been among the most critical Non-Functional Requirements. Transport Secure Layer, _aka_ TLS, formerly SSL, is among its many pillars. In this post, I'll show how to configure TLS for [Apache APISIX](https://apisix.apache.org/).
+
+<!--truncate-->
+
+<head>
+ <link rel="canonical" href="https://blog.frankel.ch/mtls-everywhere/" />
+</head>
+
+## TLS in a few words
+
+[TLS](https://wikipedia.org/wiki/Transport_Layer_Security) offers several capabilities:
+
+* Server authentication: the client is confident that the server it exchanges data with is the right one. It avoids sending data, which might be confidential, to the wrong actor
+* Optional client authentication: the other way around, the server only allows clients whose identity can be verified
+* Confidentiality: no third party can read the data exchanged between the client and the server
+* Integrity: no third party can tamper with the data
+
+TLS works through certificates. A certificate is similar to an ID, proving the certificate's holder identity. Just like an ID, you need to trust who delivered it. Trust is established through a chain: if I trust Alice, who trusts Bob, who in turn trusts Charlie, who delivered the certificate, then I trust the latter. In this scenario, Alice is known as the **root certificate authority**.
+
+TLS authentication is based on public key cryptography. Alice generates a public key/private key pair and publishes the public key. If one encrypts data with the public key, only the private key that generated the public key can decrypt them. The other usage is for one to encrypt data with the private key and everybody with the public key to decrypt it, thus proving their identity.
+
+Finally, mutual TLS, _aka_ mTLS, is the configuration of two-way TLS: server authentication to the client, as usual, but also the other way around, client authentication to the server.
+
+We now have enough understanding of the concepts to get our hands dirty.
+
+## Generating certificates with cert-manager
+
+A couple of root <abbr title="Certificate Authority">CA</abbr> are installed in browsers by default. That's how we can browse HTTPS websites safely, trusting that <https://apache.org> is the site they pretend to be. The infrastructure has no pre-installed certificates, so we must start from scratch.
+
+We need at least one root certificate. In turn, it will generate all other certificates. While it's possible to do every manually, I'll rely on [cert-manager](https://cert-manager.io/) in Kubernetes. As its name implies, cert-manager is a solution to manage certificates.
+
+Installing it with Helm is straightforward:
+
+```bash
+helm repo add jetstack https://charts.jetstack.io #1
+
+helm install \
+ cert-manager jetstack/cert-manager \
+ --namespace cert-manager \ #2
+ --create-namespace \ #2
+ --version v1.11.0 \
+ --set installCRDs=true \
+ --set prometheus.enabled=false #3
+```
+
+1. Add the charts' repository
+2. Install the objects in a dedicated namespace
+3. Don't monitor, in the scope of this post
+
+We can make sure that everything works as expected by looking at the pods:
+
+```bash
+kubectl get pods -n cert-manager
+```
+
+```
+cert-manager-cainjector-7f694c4c58-fc9bk 1/1 Running 2 (2d1h ago) 7d
+cert-manager-cc4b776cf-8p2t8 1/1 Running 1 (2d1h ago) 7d
+cert-manager-webhook-7cd8c769bb-494tl 1/1 Running 1 (2d1h ago) 7d
+```
+
+cert-manager can sign certificates from multiple sources: HashiCorp Vault, Let's Encrypt, etc. To keep things simple:
+
+* We will generate our dedicated root certificate, _i.e._, `Self-Signed`
+* We won't handle certificates rotation
+
+Let's start with the following:
+
+```yaml
+apiVersion: cert-manager.io/v1
+kind: ClusterIssuer #1
+metadata:
+ name: selfsigned-issuer
+spec:
+ selfSigned: {}
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+ name: tls #2
+---
+apiVersion: cert-manager.io/v1
+kind: Certificate #3
+metadata:
+ name: selfsigned-ca
+ namespace: tls
+spec:
+ isCA: true
+ commonName: selfsigned-ca
+ secretName: root-secret
+ issuerRef:
+ name: selfsigned-issuer
+ kind: ClusterIssuer
+ group: cert-manager.io
+---
+apiVersion: cert-manager.io/v1
+kind: Issuer #4
+metadata:
+ name: ca-issuer
+ namespace: tls
+spec:
+ ca:
+ secretName: root-secret
+```
+
+1. Certificate authority that generates certificates **cluster-wide**
+2. Create a namespace for our demo
+3. Namespaced root certificate using the cluster-wide issuer. Only used to create a namespaced issuer
+4. Namespaced issuer. Used to create all other certificates in the post
+
+After applying the previous manifest, we should be able to see the single certificate that we created:
+
+```bash
+kubectl get certificate -n tls
+```
+
+```
+NAME READY SECRET AGE
+selfsigned-ca True root-secret 7s
+```
+
+The certificate infrastructure is ready; let's look at Apache APISIX.
+
+## Quick overview of a sample Apache APISIX architecture
+
+[Apache APISIX](https://apisix.apache.org/) is an API Gateway. By default, it stores its configuration in [etcd](https://etcd.io/), a distributed key-value store - the same one used by Kubernetes. Note that in real-world scenarios, we should set up etcd clustering to improve the resiliency of the solution. For this post, we will limit ourselves to a single etcd instance. Apache APISIX offers an admin API via HTTP endpoints. Finally, the gateway forwards calls from the client to an upstream. Here's an overview of the architecture and the required certificates:
+
+
+
+Let's start with the foundational bricks: etcd and Apache APISIX. We need two certificates: one for etcd, in the server role, and one for Apache APISIX, as the etcd client.
+
+Let's set up certificates from our namespaced issuer:
+
+```yaml
+apiVersion: cert-manager.io/v1
+kind: Certificate
+metadata:
+ name: etcd-server #1
+ namespace: tls
+spec:
+ secretName: etcd-secret #2
+ isCA: false
+ usages:
+ - client auth #3
+ - server auth #3
+ dnsNames:
+ - etcd #4
+ issuerRef:
+ name: ca-issuer #5
+ kind: Issuer
+---
+apiVersion: cert-manager.io/v1
+kind: Certificate
+metadata:
+ name: apisix-client #6
+ namespace: tls
+spec:
+ secretName: apisix-client-secret
+ isCA: false
+ usages:
+ - client auth
+ emailAddresses:
+ - apisix@apache.org #7
+ issuerRef:
+ name: ca-issuer #5
+ kind: Issuer
+```
+
+1. Certificate for etcd
+2. Kubernetes `Secret` name, see below
+3. Usages for this certificate
+4. Kubernetes `Service` name, see below
+5. Reference the previously namespaced issuer created earlier
+6. Certificate for Apache APISIX as a client of etcd
+7. Mandatory attribute for clients
+
+After applying the above manifest, we can list the certificates in the `tls` namespace:
+
+```bash
+kubectl get certificates -n tls
+```
+
+```
+NAME READY SECRET AGE
+selfsigned-ca True root-secret 8m59s //1
+apisix-client True apisix-client-secret 8m22s //2
+etcd-server True etcd-secret 8m54s //2
+```
+
+1. Previously created certificate
+2. Newly-created certificates signed by `selfsigned-ca`
+
+## cert-manager's Certificates
+
+So far, we have created `Certificate` objects, but we didn't explain what they are. Indeed, they are simple Kubernetes <abbr title="Custom Resource Definition">CRD</abbr>s provided by cert-manager. Under the cover, cert-manager creates a Kubernetes `Secret` from a `Certificate`. It manages the whole lifecycle, so deleting a `Certificate` deletes the bounded `Secret`. The `secretName` attribute in the above manifest sets the `Secret` name.
+
+```bash
+kubectl get secrets -n tls
+```
+
+```
+NAME TYPE DATA AGE
+apisix-client-secret kubernetes.io/tls 3 35m
+etcd-secret kubernetes.io/tls 3 35m
+root-secret kubernetes.io/tls 3 35m
+```
+
+Let's look at a `Secret`, _e.g._, `apisix-client-secret`:
+
+```bash
+kubectl describe apisix-client-secret -n tls
+```
+
+```
+Name: apisix-client-secret
+Namespace: tls
+Labels: controller.cert-manager.io/fao=true
+Annotations: cert-manager.io/alt-names:
+ cert-manager.io/certificate-name: apisix-client
+ cert-manager.io/common-name:
+ cert-manager.io/ip-sans:
+ cert-manager.io/issuer-group:
+ cert-manager.io/issuer-kind: Issuer
+ cert-manager.io/issuer-name: ca-issuer
+ cert-manager.io/uri-sans:
+
+Type: kubernetes.io/tls
+
+Data
+====
+ca.crt: 1099 bytes
+tls.crt: 1115 bytes
+tls.key: 1679 bytes
+```
+
+A `Secret` created by a `Certificate` provides three attributes:
+
+* `tls.crt`: The certificate itself
+* `tls.key`: The private key
+* `ca.crt`: The signing certificate in the certificate chain, _i.e._, `root-secret/tls.crt`
+
+Kubernetes encodes `Secret` content in base 64. To get any of the above in plain text, one should decode it, _e.g._:
+
+```bash
+kubectl get secret etcd-secret -n tls -o jsonpath='{ .data.tls\.crt }' | base64
+```
+
+```
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+```
+
+## Configuring mTLS between etcd and APISIX
+
+With the certificates available, we can now configure mutual TLS between etcd and APISIX. Let's start with etcd:
+
+```yaml
+apiVersion: v1
+kind: Pod
+metadata:
+ name: etcd
+ namespace: tls
+ labels:
+ role: config
+spec:
+ containers:
+ - name: etcd
+ image: bitnami/etcd:3.5.7
+ ports:
+ - containerPort: 2379
+ env:
+ - name: ETCD_TRUSTED_CA_FILE #1
+ value: /etc/ssl/private/ca.crt
+ - name: ETCD_CERT_FILE #2
+ value: /etc/ssl/private/tls.crt
+ - name: ETCD_KEY_FILE #3
+ value: /etc/ssl/private/tls.key
+ - name: ETCD_ROOT_PASSWORD
+ value: whatever
+ - name: ETCD_CLIENT_CERT_AUTH #4
+ value: "true"
+ - name: ETCD_LISTEN_CLIENT_URLS
+ value: https://0.0.0.0:2379
+ volumeMounts:
+ - name: ssl
+ mountPath: /etc/ssl/private #5
+ volumes:
+ - name: ssl
+ secret:
+ secretName: etcd-secret #5
+```
+
+1. Set the trusted CA
+2. Set the certificate
+3. Set the private key
+4. Require clients to pass their certificate, hence ensuring mutual authentication
+5. Mount the previously generated secret in the container for access
+
+Now, it's Apache APISIX's turn:
+
+```yaml
+apiVersion: v1
+kind: ConfigMap #1
+metadata:
+ name: apisix-config
+ namespace: tls
+data:
+ config.yaml: >-
+ apisix:
+ ssl:
+ ssl_trusted_certificate: /etc/ssl/certs/ca.crt #2
+ deployment:
+ etcd:
+ host:
+ - https://etcd:2379
+ tls:
+ cert: /etc/ssl/certs/tls.crt #2
+ key: /etc/ssl/certs/tls.key #2
+ admin:
+ allow_admin:
+ - 0.0.0.0/0
+ https_admin: true #3
+ admin_api_mtls:
+ admin_ssl_cert: /etc/ssl/private/tls.crt #3
+ admin_ssl_cert_key: /etc/ssl/private/tls.key #3
+ admin_ssl_ca_cert: /etc/ssl/private/ca.crt #3
+---
+apiVersion: v1
+kind: Pod
+metadata:
+ name: apisix
+ namespace: tls
+ labels:
+ role: gateway
+spec:
+ containers:
+ - name: apisix
+ image: apache/apisix:3.2.0-debian
+ ports:
+ - containerPort: 9443 #4
+ - containerPort: 9180 #5
+ volumeMounts:
+ - name: config #1
+ mountPath: /usr/local/apisix/conf/config.yaml
+ subPath: config.yaml
+ - name: ssl #6
+ mountPath: /etc/ssl/private
+ - name: etcd-client #7
+ mountPath: /etc/ssl/certs
+ volumes:
+ - name: config
+ configMap:
+ name: apisix-config
+ - name: ssl #6,8
+ secret:
+ secretName: apisix-server-secret
+ - name: etcd-client #7,8
+ secret:
+ secretName: apisix-client-secret
+```
+
+1. Apache APISIX doesn't offer configuration via environment variables. We need to use a `ConfigMap` that mirrors the regular `config.yaml` file
+2. Configure _client_ authentication for etcd
+3. Configure _server_ authentication for the Admin API
+4. Regular HTTPS port
+5. Admin HTTPS port
+6. Certificates for server authentication
+7. Certificates for client authentication
+8. Two sets of certificates are used, one for server authentication for the Admin API and regular HTTPS, and one for client authentication for etcd.
+
+At this point, we can apply the above manifests and see the two pods communicating. When connecting, Apache APISIX sends its `apisix-client` certificate via HTTPS. Because an authority signs the certificate that etcd trusts, it allows the connection.
+
+I've omitted the `Service` definition for brevity's sake, but you can check them in the associated [](https://github.com/ajavageek/tls-apisix).
Review Comment:
Suggested change:
```md
I've omitted the `Service` definition for brevity's sake, but you can check them in the [associated](https://github.com/ajavageek/tls-apisix).
```
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