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| 1 | +/* |
| 2 | +Copyright 2014 The Kubernetes Authors. |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | +*/ |
| 16 | + |
| 17 | +package healthz |
| 18 | + |
| 19 | +import ( |
| 20 | + "fmt" |
| 21 | + "net/http" |
| 22 | + "path" |
| 23 | + "sort" |
| 24 | + "strings" |
| 25 | + |
| 26 | + "k8s.io/apimachinery/pkg/util/sets" |
| 27 | +) |
| 28 | + |
| 29 | +// Handler is an http.Handler that aggregates the results of the given |
| 30 | +// checkers to the root path, and supports calling individual checkers on |
| 31 | +// subpaths of the name of the checker. |
| 32 | +// |
| 33 | +// Adding checks on the fly is *not* threadsafe -- use a wrapper. |
| 34 | +type Handler struct { |
| 35 | + Checks map[string]Checker |
| 36 | +} |
| 37 | + |
| 38 | +// checkStatus holds the output of a particular check |
| 39 | +type checkStatus struct { |
| 40 | + name string |
| 41 | + healthy bool |
| 42 | + excluded bool |
| 43 | +} |
| 44 | + |
| 45 | +func (h *Handler) serveAggregated(resp http.ResponseWriter, req *http.Request) { |
| 46 | + failed := false |
| 47 | + excluded := getExcludedChecks(req) |
| 48 | + |
| 49 | + parts := make([]checkStatus, 0, len(h.Checks)) |
| 50 | + |
| 51 | + // calculate the results... |
| 52 | + for checkName, check := range h.Checks { |
| 53 | + // no-op the check if we've specified we want to exclude the check |
| 54 | + if excluded.Has(checkName) { |
| 55 | + excluded.Delete(checkName) |
| 56 | + parts = append(parts, checkStatus{name: checkName, healthy: true, excluded: true}) |
| 57 | + continue |
| 58 | + } |
| 59 | + if err := check(req); err != nil { |
| 60 | + log.V(1).Info("healthz check failed", "checker", checkName, "error", err) |
| 61 | + parts = append(parts, checkStatus{name: checkName, healthy: false}) |
| 62 | + failed = true |
| 63 | + } else { |
| 64 | + parts = append(parts, checkStatus{name: checkName, healthy: true}) |
| 65 | + } |
| 66 | + } |
| 67 | + |
| 68 | + // ...default a check if none is present... |
| 69 | + if len(h.Checks) == 0 { |
| 70 | + parts = append(parts, checkStatus{name: "ping", healthy: true}) |
| 71 | + } |
| 72 | + |
| 73 | + for _, c := range excluded.List() { |
| 74 | + log.V(1).Info("cannot exclude health check, no matches for it", "checker", c) |
| 75 | + } |
| 76 | + |
| 77 | + // ...sort to be consistent... |
| 78 | + sort.Slice(parts, func(i, j int) bool { return parts[i].name < parts[j].name }) |
| 79 | + |
| 80 | + // ...and write out the result |
| 81 | + // TODO(directxman12): this should also accept a request for JSON content (via a accept header) |
| 82 | + _, forceVerbose := req.URL.Query()["verbose"] |
| 83 | + writeStatusesAsText(resp, parts, excluded, failed, forceVerbose) |
| 84 | +} |
| 85 | + |
| 86 | +// writeStatusAsText writes out the given check statuses in some semi-arbitrary |
| 87 | +// bespoke text format that we copied from Kubernetes. unknownExcludes lists |
| 88 | +// any checks that the user requested to have excluded, but weren't actually |
| 89 | +// known checks. writeStatusAsText is always verbose on failure, and can be |
| 90 | +// forced to be verbose on success using the given argument. |
| 91 | +func writeStatusesAsText(resp http.ResponseWriter, parts []checkStatus, unknownExcludes sets.String, failed, forceVerbose bool) { |
| 92 | + resp.Header().Set("Content-Type", "text/plain; charset=utf-8") |
| 93 | + resp.Header().Set("X-Content-Type-Options", "nosniff") |
| 94 | + |
| 95 | + // always write status code first |
| 96 | + if failed { |
| 97 | + resp.WriteHeader(http.StatusInternalServerError) |
| 98 | + } else { |
| 99 | + resp.WriteHeader(http.StatusOK) |
| 100 | + } |
| 101 | + |
| 102 | + // shortcut for easy non-verbose success |
| 103 | + if !failed && !forceVerbose { |
| 104 | + fmt.Fprint(resp, "ok") |
| 105 | + return |
| 106 | + } |
| 107 | + |
| 108 | + // we're always verbose on failure, so from this point on we're guaranteed to be verbose |
| 109 | + |
| 110 | + for _, checkOut := range parts { |
| 111 | + switch { |
| 112 | + case checkOut.excluded: |
| 113 | + fmt.Fprintf(resp, "[+]%s excluded: ok\n", checkOut.name) |
| 114 | + case checkOut.healthy: |
| 115 | + fmt.Fprintf(resp, "[+]%s ok\n", checkOut.name) |
| 116 | + default: |
| 117 | + // don't include the error since this endpoint is public. If someone wants more detail |
| 118 | + // they should have explicit permission to the detailed checks. |
| 119 | + fmt.Fprintf(resp, "[-]%s failed: reason withheld\n", checkOut.name) |
| 120 | + } |
| 121 | + } |
| 122 | + |
| 123 | + if unknownExcludes.Len() > 0 { |
| 124 | + fmt.Fprintf(resp, "warn: some health checks cannot be excluded: no matches for %s\n", formatQuoted(unknownExcludes.List()...)) |
| 125 | + } |
| 126 | + |
| 127 | + if failed { |
| 128 | + log.Info("healthz check failed", "statuses", parts) |
| 129 | + fmt.Fprintf(resp, "healthz check failed\n") |
| 130 | + } else { |
| 131 | + fmt.Fprint(resp, "healthz check passed\n") |
| 132 | + } |
| 133 | +} |
| 134 | + |
| 135 | +func (h *Handler) ServeHTTP(resp http.ResponseWriter, req *http.Request) { |
| 136 | + // clean up the request (duplicating the internal logic of http.ServeMux a bit) |
| 137 | + // clean up the path a bit |
| 138 | + reqPath := req.URL.Path |
| 139 | + if reqPath == "" || reqPath[0] != '/' { |
| 140 | + reqPath = "/" + reqPath |
| 141 | + } |
| 142 | + // path.Clean removes the trailing slash except for root for us |
| 143 | + // (which is fine, since we're only serving one layer of sub-paths) |
| 144 | + reqPath = path.Clean(reqPath) |
| 145 | + |
| 146 | + // either serve the root endpoint... |
| 147 | + if reqPath == "/" { |
| 148 | + h.serveAggregated(resp, req) |
| 149 | + return |
| 150 | + } |
| 151 | + |
| 152 | + // ...the default check (if nothing else is present)... |
| 153 | + if len(h.Checks) == 0 && reqPath[1:] == "ping" { |
| 154 | + CheckHandler{Checker: Ping}.ServeHTTP(resp, req) |
| 155 | + return |
| 156 | + } |
| 157 | + |
| 158 | + // ...or an individual checker |
| 159 | + checkName := reqPath[1:] // ignore the leading slash |
| 160 | + checker, known := h.Checks[checkName] |
| 161 | + if !known { |
| 162 | + http.NotFoundHandler().ServeHTTP(resp, req) |
| 163 | + return |
| 164 | + } |
| 165 | + |
| 166 | + CheckHandler{Checker: checker}.ServeHTTP(resp, req) |
| 167 | +} |
| 168 | + |
| 169 | +// CheckHandler is an http.Handler that serves a health check endpoint at the root path, |
| 170 | +// based on its checker. |
| 171 | +type CheckHandler struct { |
| 172 | + Checker |
| 173 | +} |
| 174 | + |
| 175 | +func (h CheckHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) { |
| 176 | + err := h.Checker(req) |
| 177 | + if err != nil { |
| 178 | + http.Error(resp, fmt.Sprintf("internal server error: %v", err), http.StatusInternalServerError) |
| 179 | + } else { |
| 180 | + fmt.Fprint(resp, "ok") |
| 181 | + } |
| 182 | +} |
| 183 | + |
| 184 | +// Checker knows how to perform a health check. |
| 185 | +type Checker func(req *http.Request) error |
| 186 | + |
| 187 | +// Ping returns true automatically when checked |
| 188 | +var Ping Checker = func(_ *http.Request) error { return nil } |
| 189 | + |
| 190 | +// getExcludedChecks extracts the health check names to be excluded from the query param |
| 191 | +func getExcludedChecks(r *http.Request) sets.String { |
| 192 | + checks, found := r.URL.Query()["exclude"] |
| 193 | + if found { |
| 194 | + return sets.NewString(checks...) |
| 195 | + } |
| 196 | + return sets.NewString() |
| 197 | +} |
| 198 | + |
| 199 | +// formatQuoted returns a formatted string of the health check names, |
| 200 | +// preserving the order passed in. |
| 201 | +func formatQuoted(names ...string) string { |
| 202 | + quoted := make([]string, 0, len(names)) |
| 203 | + for _, name := range names { |
| 204 | + quoted = append(quoted, fmt.Sprintf("%q", name)) |
| 205 | + } |
| 206 | + return strings.Join(quoted, ",") |
| 207 | +} |
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