Add custom certificate CA support for s3

CHANGELOG.md

@@ -34,6 +34,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#4942](https://github.com/thanos-io/thanos/pull/4942) Tracing: add `traceid_128bit` support for jaeger.
 - [#4917](https://github.com/thanos-io/thanos/pull/4917) Query: add initial query pushdown for a subset of aggregations. Can be enabled with `--enable-feature=query-pushdown` on Thanos Query.
 - [#4888](https://github.com/thanos-io/thanos/pull/4888) Cache: support redis cache backend.
+- [#4946](https://github.com/thanos-io/thanos/pull/4946) Store: Support tls_config configuration for the s3 minio client.
 
 ### Fixed
 

docs/storage.md

@@ -79,6 +79,12 @@ config:
     max_idle_conns: 100
     max_idle_conns_per_host: 100
     max_conns_per_host: 0
+    tls_config:
+      ca_file: ""
+      cert_file: ""
+      key_file: ""
+      server_name: ""
+      insecure_skip_verify: false
   trace:
     enable: false
   list_objects_version: ""
@@ -105,6 +111,8 @@ Please refer to the documentation of [the Transport type](https://golang.org/pkg
 
 Set `list_objects_version: "v1"` for S3 compatible APIs that don't support ListObjectsV2 (e.g. some versions of Ceph). Default value (`""`) is equivalent to `"v2"`.
 
+`http_config.tls_config` allows configuring TLS connections. Please refer to the document of [tls_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#tls_config) for detailed information on what each option does.
+
 For debug and testing purposes you can set
 
 * `insecure: true` to switch to plain insecure HTTP instead of HTTPS

pkg/objstore/s3/s3.go

@@ -7,6 +7,7 @@ package s3
 import (
 	"context"
 	"crypto/tls"
+	"crypto/x509"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -117,13 +118,100 @@ type HTTPConfig struct {
 
 	// Allow upstream callers to inject a round tripper
 	Transport http.RoundTripper `yaml:"-"`
+
+	TLSConfig TLSConfig `yaml:"tls_config"`
+}
+
+// NewTLSConfig creates a new tls.Config from the given TLSConfig.
+func NewTLSConfig(cfg *TLSConfig) (*tls.Config, error) {
+	tlsConfig := &tls.Config{InsecureSkipVerify: cfg.InsecureSkipVerify}
+
+	// If a CA cert is provided then let's read it in.
+	if len(cfg.CAFile) > 0 {
+		b, err := readCAFile(cfg.CAFile)
+		if err != nil {
+			return nil, err
+		}
+		if !updateRootCA(tlsConfig, b) {
+			return nil, fmt.Errorf("unable to use specified CA cert %s", cfg.CAFile)
+		}
+	}
+
+	if len(cfg.ServerName) > 0 {
+		tlsConfig.ServerName = cfg.ServerName
+	}
+	// If a client cert & key is provided then configure TLS config accordingly.
+	if len(cfg.CertFile) > 0 && len(cfg.KeyFile) == 0 {
+		return nil, fmt.Errorf("client cert file %q specified without client key file", cfg.CertFile)
+	} else if len(cfg.KeyFile) > 0 && len(cfg.CertFile) == 0 {
+		return nil, fmt.Errorf("client key file %q specified without client cert file", cfg.KeyFile)
+	} else if len(cfg.CertFile) > 0 && len(cfg.KeyFile) > 0 {
+		// Verify that client cert and key are valid.
+		if _, err := cfg.getClientCertificate(nil); err != nil {
+			return nil, err
+		}
+		tlsConfig.GetClientCertificate = cfg.getClientCertificate
+	}
+
+	return tlsConfig, nil
+}
+
+// readCAFile reads the CA cert file from disk.
+func readCAFile(f string) ([]byte, error) {
+	data, err := ioutil.ReadFile(f)
+	if err != nil {
+		return nil, fmt.Errorf("unable to load specified CA cert %s: %s", f, err)
+	}
+	return data, nil
+}
+
+// updateRootCA parses the given byte slice as a series of PEM encoded certificates and updates tls.Config.RootCAs.
+func updateRootCA(cfg *tls.Config, b []byte) bool {
+	caCertPool := x509.NewCertPool()
+	if !caCertPool.AppendCertsFromPEM(b) {
+		return false
+	}
+	cfg.RootCAs = caCertPool
+	return true
+}
+
+// getClientCertificate reads the pair of client cert and key from disk and returns a tls.Certificate.
+func (c *TLSConfig) getClientCertificate(*tls.CertificateRequestInfo) (*tls.Certificate, error) {
+	cert, err := tls.LoadX509KeyPair(c.CertFile, c.KeyFile)
+	if err != nil {
+		return nil, fmt.Errorf("unable to use specified client cert (%s) & key (%s): %s", c.CertFile, c.KeyFile, err)
+	}
+	return &cert, nil
+}
+
+// TLSConfig configures the options for TLS connections.
+type TLSConfig struct {
+	// The CA cert to use for the targets.
+	CAFile string `yaml:"ca_file"`
+	// The client cert file for the targets.
+	CertFile string `yaml:"cert_file"`
+	// The client key file for the targets.
+	KeyFile string `yaml:"key_file"`
+	// Used to verify the hostname for the targets.
+	ServerName string `yaml:"server_name"`
+	// Disable target certificate validation.
+	InsecureSkipVerify bool `yaml:"insecure_skip_verify"`
 }
 
 // DefaultTransport - this default transport is based on the Minio
 // DefaultTransport up until the following commit:
 // https://github.com/minio/minio-go/commit/008c7aa71fc17e11bf980c209a4f8c4d687fc884
 // The values have since diverged.
-func DefaultTransport(config Config) *http.Transport {
+func DefaultTransport(config Config) (*http.Transport, error) {
+	tlsConfig, err := NewTLSConfig(&config.HTTPConfig.TLSConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	if config.HTTPConfig.InsecureSkipVerify {
+		tlsConfig.InsecureSkipVerify = true
+	}
+
 	return &http.Transport{
 		Proxy: http.ProxyFromEnvironment,
 		DialContext: (&net.Dialer{
@@ -148,8 +236,8 @@ func DefaultTransport(config Config) *http.Transport {
 		//
 		// Refer: https://golang.org/src/net/http/transport.go?h=roundTrip#L1843.
 		DisableCompression: true,
-		TLSClientConfig:    &tls.Config{InsecureSkipVerify: config.HTTPConfig.InsecureSkipVerify},
-	}
+		TLSClientConfig:    tlsConfig,
+	}, nil
 }
 
 // Bucket implements the store.Bucket interface against s3-compatible APIs.
@@ -241,7 +329,11 @@ func NewBucketWithConfig(logger log.Logger, config Config, component string) (*B
 	if config.HTTPConfig.Transport != nil {
 		rt = config.HTTPConfig.Transport
 	} else {
-		rt = DefaultTransport(config)
+		var err error
+		rt, err = DefaultTransport(config)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	client, err := minio.New(config.Endpoint, &minio.Options{

pkg/objstore/s3/s3_test.go

@@ -163,6 +163,42 @@ http_config:
 	}
 }
 
+func TestParseConfig_CustomHTTPConfigWithTLS(t *testing.T) {
+	input := []byte(`bucket: abcd
+insecure: false
+http_config:
+  tls_config:
+    ca_file: /certs/ca.crt
+    cert_file: /certs/cert.crt
+    key_file: /certs/key.key
+    server_name: server
+    insecure_skip_verify: false
+  `)
+	cfg, err := parseConfig(input)
+	testutil.Ok(t, err)
+
+	testutil.Equals(t, "/certs/ca.crt", cfg.HTTPConfig.TLSConfig.CAFile)
+	testutil.Equals(t, "/certs/cert.crt", cfg.HTTPConfig.TLSConfig.CertFile)
+	testutil.Equals(t, "/certs/key.key", cfg.HTTPConfig.TLSConfig.KeyFile)
+	testutil.Equals(t, "server", cfg.HTTPConfig.TLSConfig.ServerName)
+	testutil.Equals(t, false, cfg.HTTPConfig.TLSConfig.InsecureSkipVerify)
+}
+
+func TestParseConfig_CustomLegacyInsecureSkipVerify(t *testing.T) {
+	input := []byte(`bucket: abcd
+insecure: false
+http_config:
+  insecure_skip_verify: true
+  tls_config:
+    insecure_skip_verify: false
+  `)
+	cfg, err := parseConfig(input)
+	testutil.Ok(t, err)
+	transport, err := DefaultTransport(cfg)
+	testutil.Ok(t, err)
+	testutil.Equals(t, true, transport.TLSClientConfig.InsecureSkipVerify)
+}
+
 func TestValidate_OK(t *testing.T) {
 	input := []byte(`bucket: "bucket-name"
 endpoint: "s3-endpoint"