Improve documentation for ACME/Let's Encrypt

docs/content/https/.markdownlint.json

@@ -0,0 +1,4 @@
+{
+    "extends": "../../.markdownlint.json",
+    "MD041": false
+}

docs/content/https/acme.md

@@ -8,6 +8,45 @@ You can configure Traefik to use an ACME provider (like Let's Encrypt) for autom
 !!! warning "Let's Encrypt and Rate Limiting"
     Note that Let's Encrypt API has [rate limiting](https://letsencrypt.org/docs/rate-limits).
 
+    Use Let's Encrypt staging server with the [`caServer`](#caserver) configuration option
+    when experimenting to avoid hitting this limit too fast.
+    
+## Certificate Resolvers
+
+Traefik requires you to define "Certificate Resolvers" in the [static configuration](../getting-started/configuration-overview.md#the-static-configuration), 
+which are responsible for retrieving certificates from an ACME server.
+
+Then, each ["router"](../routing/routers/index.md) is configured to enable TLS,
+and is associated to a certificate resolver through the [`tls.certresolver` configuration option](../routing/routers/index.md#certresolver).
+
+Certificates are requested for domain names retrieved from the router's [dynamic configuration](../getting-started/configuration-overview.md#the-dynamic-configuration).
+
+You can read more about this retrieval mechanism in the following section: [ACME Domain Definition](#domain-definition).
+
+## Domain Definition
+
+Certificate resolvers request certificates for a set of the domain names 
+inferred from routers, with the following logic:
+
+- If the router has a [`tls.domains`](../routing/routers/index.md#domains) option set,
+  then the certificate resolver uses the `main` (and optionally `sans`) option of `tls.domains` to know the domain names for this router.
+
+- If no [`tls.domains`](../routing/routers/index.md#domains) option is set, 
+  then the certificate resolver uses the [router's rule](../routing/routers/index.md#rule), 
+  by checking the `Host()` matchers. 
+  Please note that [multiple `Host()` matchers can be used](../routing/routers/index.md#certresolver)) for specifying multiple domain names for this router.
+
+Please note that:
+
+- When multiple domain names are inferred from a given router,
+  only **one** certificate is requested with the first domain name as the main domain,
+  and the other domains as ["SANs" (Subject Alternative Name)](https://en.wikipedia.org/wiki/Subject_Alternative_Name).
+
+- As [ACME V2 supports "wildcard domains"](#wildcard-domains),
+  any router can provide a [wildcard domain](https://en.wikipedia.org/wiki/Wildcard_certificate) name, as "main" domain or as "SAN" domain.
+
+Please check the [configuration examples below](#configuration-examples) for more details.
+
 ## Configuration Examples
 
 ??? example "Enabling ACME"
@@ -75,6 +114,26 @@ You can configure Traefik to use an ACME provider (like Let's Encrypt) for autom
     --8<-- "content/https/ref-acme.txt"
     ```
 
+??? example "Single Domain from Router's Rule Example"
+    
+    * A certificate for the domain `company.com` is requested:
+
+    --8<-- "content/https/include-acme-single-domain-example.md"
+
+??? example "Multiple Domains from Router's Rule Example"
+ 
+    * A certificate for the domains `company.com` (main) and `blog.company.org`
+      is requested:
+    
+    --8<-- "content/https/include-acme-multiple-domains-from-rule-example.md"
+    
+??? example "Multiple Domains from Router's `tls.domain` Example"
+
+    * A certificate for the domains `company.com` (main) and `*.company.org` (SAN)
+      is requested:
+      
+    --8<-- "content/https/include-acme-multiple-domains-example.md"
+
 ## Automatic Renewals
 
 Traefik automatically tracks the expiry date of ACME certificates it generates.
@@ -327,7 +386,9 @@ certificatesResolvers:
 [ACME V2](https://community.letsencrypt.org/t/acme-v2-and-wildcard-certificate-support-is-live/55579) supports wildcard certificates.
 As described in [Let's Encrypt's post](https://community.letsencrypt.org/t/staging-endpoint-for-acme-v2/49605) wildcard certificates can only be generated through a [`DNS-01` challenge](#dnschallenge).
 
-## `caServer`
+## More Configuration
+
+### `caServer`
 
 ??? example "Using the Let's Encrypt staging server"
 
@@ -353,7 +414,7 @@ As described in [Let's Encrypt's post](https://community.letsencrypt.org/t/stagi
     # ...
     ```
 
-## `storage`
+### `storage`
 
 The `storage` option sets the location where your ACME certificates are saved to.
 
@@ -383,7 +444,7 @@ The value can refer to some kinds of storage:
 
 - a JSON file
 
-### In a File
+#### In a File
 
 ACME certificates can be stored in a JSON file that needs to have a `600` file mode .
 

docs/content/https/include-acme-multiple-domains-example.md

@@ -0,0 +1,88 @@
+
+```yaml tab="Docker"
+## Dynamic configuration
+labels:
+  - traefik.http.routers.blog.rule=Host(`company.com`) && Path(`/blog`)
+  - traefik.http.routers.blog.tls=true
+  - traefik.http.routers.blog.tls.certresolver=le
+  - traefik.http.routers.blog.tls.domains[0].main=company.org
+  - traefik.http.routers.blog.tls.domains[0].sans=*.company.org
+```
+
+```yaml tab="Docker (Swarm)"
+## Dynamic configuration
+deploy:
+  labels:
+    - traefik.http.routers.blog.rule=Host(`company.com`) && Path(`/blog`)
+    - traefik.http.services.blog-svc.loadbalancer.server.port=8080"
+    - traefik.http.routers.blog.tls=true
+    - traefik.http.routers.blog.tls.certresolver=le
+    - traefik.http.routers.blog.tls.domains[0].main=company.org
+    - traefik.http.routers.blog.tls.domains[0].sans=*.company.org
+```
+
+```yaml tab="Kubernetes"
+---
+apiVersion: traefik.containo.us/v1alpha1
+kind: IngressRoute
+metadata:
+  name: blogtls
+spec:
+  entryPoints:
+    - websecure
+  routes:
+  - match: Host(`company.com`) && Path(`/blog`)
+    kind: Rule
+    services:
+    - name: blog
+      port: 8080
+  tls:
+    certResolver: le
+```
+
+```json tab="Marathon"
+labels: {
+  "traefik.http.routers.blog.rule": "Host(`company.com`) && Path(`/blog`)",
+  "traefik.http.routers.blog.tls": "true",
+  "traefik.http.routers.blog.tls.certresolver": "le",
+  "traefik.http.routers.blog.tls.domains[0].main": "company.com",
+  "traefik.http.routers.blog.tls.domains[0].sans": "*.company.com",
+  "traefik.http.services.blog-svc.loadbalancer.server.port": "8080"
+}
+```
+
+```yaml tab="Rancher"
+## Dynamic configuration
+labels:
+  - traefik.http.routers.blog.rule=Host(`company.com`) && Path(`/blog`)
+  - traefik.http.routers.blog.tls=true
+  - traefik.http.routers.blog.tls.certresolver=le
+  - traefik.http.routers.blog.tls.domains[0].main=company.org
+  - traefik.http.routers.blog.tls.domains[0].sans=*.company.org
+```
+
+```toml tab="File (TOML)"
+## Dynamic configuration
+[http.routers]
+  [http.routers.blog]
+    rule = "Host(`company.com`) && Path(`/blog`)"
+    [http.routers.blog.tls]
+      certResolver = "le" # From static configuration
+      [[http.routers.blog.tls.domains]]
+        main = "company.org"
+        sans = ["*.company.org"]
+```
+
+```yaml tab="File (YAML)"
+## Dynamic configuration
+http:
+  routers:
+    blog:
+      rule: "Host(`company.com`) && Path(`/blog`)"
+      tls:
+        certResolver: le
+        domains:
+          - main: "company.org"
+            sans:
+              - "*.company.org"
+```

docs/content/https/include-acme-multiple-domains-from-rule-example.md

@@ -0,0 +1,72 @@
+
+```yaml tab="Docker"
+## Dynamic configuration
+labels:
+  - traefik.http.routers.blog.rule=(Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)
+  - traefik.http.routers.blog.tls=true
+  - traefik.http.routers.blog.tls.certresolver=le
+```
+
+```yaml tab="Docker (Swarm)"
+## Dynamic configuration
+deploy:
+  labels:
+    - traefik.http.routers.blog.rule=(Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)
+    - traefik.http.services.blog-svc.loadbalancer.server.port=8080"
+    - traefik.http.routers.blog.tls=true
+    - traefik.http.routers.blog.tls.certresolver=le
+```
+
+```yaml tab="Kubernetes"
+---
+apiVersion: traefik.containo.us/v1alpha1
+kind: IngressRoute
+metadata:
+  name: blogtls
+spec:
+  entryPoints:
+    - websecure
+  routes:
+  - match: (Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)
+    kind: Rule
+    services:
+    - name: blog
+      port: 8080
+  tls: {}
+```
+
+```json tab="Marathon"
+labels: {
+  "traefik.http.routers.blog.rule": "(Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)",
+  "traefik.http.routers.blog.tls": "true",
+  "traefik.http.routers.blog.tls.certresolver": "le",
+  "traefik.http.services.blog-svc.loadbalancer.server.port": "8080"
+}
+```
+
+```yaml tab="Rancher"
+## Dynamic configuration
+labels:
+  - traefik.http.routers.blog.rule=(Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)
+  - traefik.http.routers.blog.tls=true
+  - traefik.http.routers.blog.tls.certresolver=le
+```
+
+```toml tab="File (TOML)"
+## Dynamic configuration
+[http.routers]
+  [http.routers.blog]
+    rule = "(Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)"
+    [http.routers.blog.tls]
+      certResolver = "le" # From static configuration
+```
+
+```yaml tab="File (YAML)"
+## Dynamic configuration
+http:
+  routers:
+    blog:
+      rule: "(Host(`company.com`) && Path(`/blog`)) || Host(`blog.company.org`)"
+      tls:
+        certResolver: le
+```

docs/content/https/include-acme-single-domain-example.md

@@ -0,0 +1,72 @@
+
+```yaml tab="Docker"
+## Dynamic configuration
+labels:
+  - traefik.http.routers.blog.rule=Host(`company.com`) && Path(`/blog`)
+  - traefik.http.routers.blog.tls=true
+  - traefik.http.routers.blog.tls.certresolver=le
+```
+
+```yaml tab="Docker (Swarm)"
+## Dynamic configuration
+deploy:
+  labels:
+    - traefik.http.routers.blog.rule=Host(`company.com`) && Path(`/blog`)
+    - traefik.http.services.blog-svc.loadbalancer.server.port=8080"
+    - traefik.http.routers.blog.tls=true
+    - traefik.http.routers.blog.tls.certresolver=le
+```
+
+```yaml tab="Kubernetes"
+---
+apiVersion: traefik.containo.us/v1alpha1
+kind: IngressRoute
+metadata:
+  name: blogtls
+spec:
+  entryPoints:
+    - websecure
+  routes:
+  - match: Host(`company.com`) && Path(`/blog`)
+    kind: Rule
+    services:
+    - name: blog
+      port: 8080
+  tls: {}
+```
+
+```json tab="Marathon"
+labels: {
+  "traefik.http.routers.blog.rule": "Host(`company.com`) && Path(`/blog`)",
+  "traefik.http.routers.blog.tls": "true",
+  "traefik.http.routers.blog.tls.certresolver": "le",
+  "traefik.http.services.blog-svc.loadbalancer.server.port": "8080"
+}
+```
+
+```yaml tab="Rancher"
+## Dynamic configuration
+labels:
+  - traefik.http.routers.blog.rule=Host(`company.com`) && Path(`/blog`)
+  - traefik.http.routers.blog.tls=true
+  - traefik.http.routers.blog.tls.certresolver=le
+```
+
+```toml tab="Single Domain"
+## Dynamic configuration
+[http.routers]
+    [http.routers.blog]
+    rule = "Host(`company.com`) && Path(`/blog`)"
+    [http.routers.blog.tls]
+        certResolver = "le" # From static configuration
+```
+
+```yaml tab="File (YAML)"
+## Dynamic configuration
+http:
+  routers:
+    blog:
+      rule: "Host(`company.com`) && Path(`/blog`)"
+      tls:
+        certResolver: le
+```

docs/content/index.md

@@ -20,4 +20,4 @@ Developing Traefik, our main goal is to make it simple to use, and we're sure yo
 
 !!! info
 
-    If you're a business running critical services behind Traefik, know that [Containous](https://containo.us), the company that sponsors Traefik's development, can provide [commercial support](https://containo.us/services/#commercial-support) and develops an [Enterprise Edition](https://containo.us/traefikee/) of Traefik. 
+    If you're a business running critical services behind Traefik, know that [Containous](https://containo.us), the company that sponsors Traefik's development, can provide [commercial support](https://info.containo.us/commercial-services) and develops an [Enterprise Edition](https://containo.us/traefikee/) of Traefik. 

docs/content/routing/providers/marathon.md

@@ -91,7 +91,7 @@ For example, to change the routing rule, you could add the label ```"traefik.htt
     See [tls](../routers/index.md#tls) for more information.
     
     ```json
-    "traefik.http.routers.myrouter>.tls": "true"
+    "traefik.http.routers.myrouter.tls": "true"
     ```
 
 ??? info "`traefik.http.routers.<router_name>.tls.certresolver`"

docs/mkdocs.yml

@@ -44,7 +44,7 @@ plugins:
   - search
   - exclude:
       glob:
-        - include-*.md
+        - "**/include-*.md"
 
 # https://squidfunk.github.io/mkdocs-material/extensions/admonition/
 # https://facelessuser.github.io/pymdown-extensions/