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[ENHANCEMEN] Remote-Write: optionally use a DNS resolver that picks a…
… random IP (#15329) When a remote-write is executed towards a host name that is resolved to multiple IP addresses, this PR introduces a possibility to force creation of new connections used for the remote-write request to a randomly chosen IP address from the ones corresponding to the host name. The default behavior remains unchanged, i.s., the IP address used for the connection creation remains the one chosen by Go. This is an experimental feature, it is disabled by default. Signed-off-by: Yuri Nikolic <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,62 @@ | ||
| // Copyright 2024 The Prometheus Authors | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package remote | ||
|
|
||
| import ( | ||
| "context" | ||
| "math/rand" | ||
| "net" | ||
| "net/http" | ||
| "time" | ||
|
|
||
| "github.com/prometheus/common/config" | ||
| ) | ||
|
|
||
| type hostResolver interface { | ||
| LookupHost(context.Context, string) ([]string, error) | ||
| } | ||
|
|
||
| type dialContextWithRoundRobinDNS struct { | ||
| dialContext config.DialContextFunc | ||
| resolver hostResolver | ||
| rand *rand.Rand | ||
| } | ||
|
|
||
| // newDialContextWithRoundRobinDNS creates a new dialContextWithRoundRobinDNS. | ||
| // We discourage creating new instances of struct dialContextWithRoundRobinDNS by explicitly setting its members, | ||
| // except for testing purposes, and recommend using newDialContextWithRoundRobinDNS. | ||
| func newDialContextWithRoundRobinDNS() *dialContextWithRoundRobinDNS { | ||
| return &dialContextWithRoundRobinDNS{ | ||
| dialContext: http.DefaultTransport.(*http.Transport).DialContext, | ||
| resolver: net.DefaultResolver, | ||
| rand: rand.New(rand.NewSource(time.Now().Unix())), | ||
| } | ||
| } | ||
|
|
||
| func (dc *dialContextWithRoundRobinDNS) dialContextFn() config.DialContextFunc { | ||
| return func(ctx context.Context, network, addr string) (net.Conn, error) { | ||
| host, port, err := net.SplitHostPort(addr) | ||
| if err != nil { | ||
| return dc.dialContext(ctx, network, addr) | ||
| } | ||
|
|
||
| addrs, err := dc.resolver.LookupHost(ctx, host) | ||
| if err != nil || len(addrs) == 0 { | ||
| return dc.dialContext(ctx, network, addr) | ||
| } | ||
|
|
||
| randomAddr := net.JoinHostPort(addrs[dc.rand.Intn(len(addrs))], port) | ||
| return dc.dialContext(ctx, network, randomAddr) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,161 @@ | ||
| // Copyright 2024 The Prometheus Authors | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package remote | ||
|
|
||
| import ( | ||
| "context" | ||
| "errors" | ||
| "math/rand" | ||
| "net" | ||
| "sync" | ||
| "testing" | ||
| "time" | ||
|
|
||
| "github.com/prometheus/common/config" | ||
| "github.com/stretchr/testify/mock" | ||
| "github.com/stretchr/testify/require" | ||
| ) | ||
|
|
||
| const ( | ||
| testNetwork = "tcp" | ||
| testAddrWithoutPort = "this-is-my-addr.without-port" | ||
| testAddrWithPort = "this-is-my-addr.without-port:123" | ||
| testPort = "123" | ||
| ip1 = "1.2.3.4" | ||
| ip2 = "5.6.7.8" | ||
| ip3 = "9.0.1.2" | ||
| randSeed int64 = 123456789 | ||
| ) | ||
|
|
||
| var ( | ||
| errMockLookupHost = errors.New("this is a mocked error") | ||
| testLookupResult = []string{ip1, ip2, ip3} | ||
| testLookupResultWithPort = []string{net.JoinHostPort(ip1, testPort), net.JoinHostPort(ip2, testPort), net.JoinHostPort(ip3, testPort)} | ||
| ) | ||
|
|
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| type mockDialContext struct { | ||
| mock.Mock | ||
|
|
||
| addrFrequencyMu sync.Mutex | ||
| addrFrequency map[string]int | ||
| } | ||
|
|
||
| func newMockDialContext(acceptableAddresses []string) *mockDialContext { | ||
| m := &mockDialContext{ | ||
| addrFrequencyMu: sync.Mutex{}, | ||
| addrFrequency: make(map[string]int), | ||
| } | ||
| for _, acceptableAddr := range acceptableAddresses { | ||
| m.On("dialContext", mock.Anything, mock.Anything, acceptableAddr).Return(nil, nil) | ||
| } | ||
| return m | ||
| } | ||
|
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| func (dc *mockDialContext) dialContext(ctx context.Context, network, addr string) (net.Conn, error) { | ||
| dc.addrFrequencyMu.Lock() | ||
| defer dc.addrFrequencyMu.Unlock() | ||
| args := dc.MethodCalled("dialContext", ctx, network, addr) | ||
| dc.addrFrequency[addr]++ | ||
| return nil, args.Error(1) | ||
| } | ||
|
|
||
| func (dc *mockDialContext) getCount(addr string) int { | ||
| dc.addrFrequencyMu.Lock() | ||
| defer dc.addrFrequencyMu.Unlock() | ||
| return dc.addrFrequency[addr] | ||
| } | ||
|
|
||
| type mockedLookupHost struct { | ||
| withErr bool | ||
| result []string | ||
| } | ||
|
|
||
| func (lh *mockedLookupHost) LookupHost(context.Context, string) ([]string, error) { | ||
| if lh.withErr { | ||
| return nil, errMockLookupHost | ||
| } | ||
| return lh.result, nil | ||
| } | ||
|
|
||
| func createDialContextWithRoundRobinDNS(dialContext config.DialContextFunc, resolver hostResolver, r *rand.Rand) dialContextWithRoundRobinDNS { | ||
| return dialContextWithRoundRobinDNS{ | ||
| dialContext: dialContext, | ||
| resolver: resolver, | ||
| rand: r, | ||
| } | ||
| } | ||
|
|
||
| func TestDialContextWithRandomConnections(t *testing.T) { | ||
| numberOfRuns := 2 * len(testLookupResult) | ||
| var mdc *mockDialContext | ||
| testCases := map[string]struct { | ||
| addr string | ||
| setup func() dialContextWithRoundRobinDNS | ||
| check func() | ||
| }{ | ||
| "if address contains no port call default DealContext": { | ||
| addr: testAddrWithoutPort, | ||
| setup: func() dialContextWithRoundRobinDNS { | ||
| mdc = newMockDialContext([]string{testAddrWithoutPort}) | ||
| return createDialContextWithRoundRobinDNS(mdc.dialContext, &mockedLookupHost{withErr: false}, rand.New(rand.NewSource(time.Now().Unix()))) | ||
| }, | ||
| check: func() { | ||
| require.Equal(t, numberOfRuns, mdc.getCount(testAddrWithoutPort)) | ||
| }, | ||
| }, | ||
| "if lookup host returns error call default DealContext": { | ||
| addr: testAddrWithPort, | ||
| setup: func() dialContextWithRoundRobinDNS { | ||
| mdc = newMockDialContext([]string{testAddrWithPort}) | ||
| return createDialContextWithRoundRobinDNS(mdc.dialContext, &mockedLookupHost{withErr: true}, rand.New(rand.NewSource(time.Now().Unix()))) | ||
| }, | ||
| check: func() { | ||
| require.Equal(t, numberOfRuns, mdc.getCount(testAddrWithPort)) | ||
| }, | ||
| }, | ||
| "if lookup returns no addresses call default DealContext": { | ||
| addr: testAddrWithPort, | ||
| setup: func() dialContextWithRoundRobinDNS { | ||
| mdc = newMockDialContext([]string{testAddrWithPort}) | ||
| return createDialContextWithRoundRobinDNS(mdc.dialContext, &mockedLookupHost{}, rand.New(rand.NewSource(time.Now().Unix()))) | ||
| }, | ||
| check: func() { | ||
| require.Equal(t, numberOfRuns, mdc.getCount(testAddrWithPort)) | ||
| }, | ||
| }, | ||
| "if lookup host is successful, shuffle results": { | ||
| addr: testAddrWithPort, | ||
| setup: func() dialContextWithRoundRobinDNS { | ||
| mdc = newMockDialContext(testLookupResultWithPort) | ||
| return createDialContextWithRoundRobinDNS(mdc.dialContext, &mockedLookupHost{result: testLookupResult}, rand.New(rand.NewSource(randSeed))) | ||
| }, | ||
| check: func() { | ||
| // we ensure that not all runs will choose the first element of the lookup | ||
| require.NotEqual(t, numberOfRuns, mdc.getCount(testLookupResultWithPort[0])) | ||
| }, | ||
| }, | ||
| } | ||
|
|
||
| for name, tc := range testCases { | ||
| t.Run(name, func(t *testing.T) { | ||
| dc := tc.setup() | ||
| require.NotNil(t, dc) | ||
| for i := 0; i < numberOfRuns; i++ { | ||
| _, err := dc.dialContextFn()(context.Background(), testNetwork, tc.addr) | ||
| require.NoError(t, err) | ||
| } | ||
| tc.check() | ||
| }) | ||
| } | ||
| } |
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